Torque transmitting apparatus

ABSTRACT

A hydrokinetic torque converter with a built-in bypass clutch is provided with an arrangement which regulates the cooling of the clutch at a rate dependent upon the slip between the coaxial driving and driven parts of the clutch, and hence upon the quantity of generated friction heat. The cooling unit for the driving and/or driven part of the clutch can employ, for example, one or more pumps; a supply of a substance which changes its aggregate state from liquid to gaseous or from solid to flowable in response to heating, and vice versa in response to cooling; one or more porous washers in the path for the flow of hydraulic fluid between the customary plenum chambers provided in the housing of the torque converter to move a piston of the driven part of the clutch into and from frictional engagement with the housing; and/or a system of recesses, grooves, channels and/or other passages serving to convey fluid between the chambers at a rate which is higher or highest when the clutch operates with maximum slip. Such rate can decrease to zero when the torque converter is idle or the clutch is fully engaged to operate without slip.

CROSS-REFERENCE TO RELATED CASES

The present application is a divisional of U.S. patent application Ser.No. 09/842,362, filed Apr. 25, 2001, now U.S. Pat. No. 6,851,532 whichclaims the priority of the commonly owned German patent application Ser.No. 100 20 907.6, filed Apr. 28, 2000. The disclosure of theabove-referenced patent applications, as well as that of each US andforeign patent and patent application identified in the specification ofthe present application are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to improvements in torque transmittingapparatus, and more particularly to improvements in hydrokinetic torqueconverters of the type often utilized in the power trains of motorvehicles, e.g., to transit torque between the output element of a primemover (such as a crankshaft or a camshaft of a combustion engine) andthe input shaft of a change-speed transmission.

A torque converter of the character to which the present inventionpertains normally comprises a rotary housing which is driven by theprime mover and drives a vaned pump, a vaned turbine which can berotated by the body of fluid filling the housing and being circulated bythe pump when the prime mover is on, an optional stator between the pumpand the turbine, and a so-called bypass clutch or lockup clutch(hereinafter called bypass clutch) which can be engaged to transmittorque from the housing directly to the turbine or to a hub whichrotates with the turbine and serves to transmit torque to the inputshaft of the transmission.

The bypass clutch can operate with or without slip and is engageable anddisengageable by moving a piston into or from full or partial frictionalengagement with a portion of the housing or with a part which rotateswith the housing. The housing contains two fluid-filled plenum chambersand the piston is moved axially to partly or fully engage or disengagethe clutch in response to changes of pressure differential between thebodies of fluid filling the two plenum chambers. The torque converteroften further comprises one or more torsional vibration dampersoperating between the housing and the turbine and/or between the turbineand the hub.

A torque converter of the above outlined character is disclosed, forexample, in German patent No. 36 14 158. The patented apparatus employsa bypass clutch which operates between the housing and an axiallymovable piston which rotates with the hub. Such apparatus are known astwin-channel torque converters wherein the piston of or for the bypassclutch separates the plenum chambers from each other when the bypassclutch is at least partially engaged so that a friction lining on thepiston engages and receives torque from a portion (e.g., a radial wall)of the housing or from a friction lining on the housing. Partialengagement of the bypass clutch involves a slip of the piston relativeto the housing and/or vice versa, and such slip results in thegeneration of heat in such quantities that the fluid medium in thehousing of the torque converter is not always capable of absorbingexcess heat. Excessive heating of friction linings forming part of thebypass clutch can entail damage to and frequently rapid destruction ofthe friction linings; in addition, overheating can adversely influencethe hydraulic fluid in the housing of the torque converter.

Abrupt full engagement of the bypass clutch, i.e., without slip, islikely to be even more damaging to the torque converter and can alsoadversely affect the comfort to the occupant(s) of the motor vehicle.Thus, an abrupt transition from disengagement to full engagement of thebypass clutch can be a cause of discomfort to the occupant(s). In otherwords, the ride is much more comfortable if the bypass clutch of thetorque converter is engaged gradually with an initially pronounced andthereupon gradually decreasing slip, i.e., with the generation of largequantities of undesirable friction heat. Thus, it is desirable to devisea torque converter wherein the bypass clutch is fully engaged. upon agradual reduction of slip but the thus developing large quantities offriction heat can be dissipated and/or otherwise disposed of withoutaffecting the comfort to the occupant(s) of the motor vehicle (if thetorque converter is installed in the power train of a motor vehicle) andwithout damage to the friction linings and/or other heat-sensitive partsof the torque converter and of its bypass clutch. Such requirementscannot be met, or cannot be adequately satisfied, by presently knowntorque converters. It is also desirable and important to ensure that thewithdrawal of requisite quantities of heat be effected without undulyincreasing the space requirements of the torque converter, especially inthe power train of a motor vehicle.

OBJECTS OF THE INVENTION

An object of the instant invention is to provide a novel and improvedarrangement which renders it possible to withdraw heat from and/or todissipate heat in a torque converter at a rate which is required toavoid damage to various heated heat-sensitive parts and/or substances,such as friction linings, oil, transmission fluid and the like.

Another object of the invention is to provide a simple, compact andrelatively inexpensive heat exchange system which can be incorporated inexisting types of hydrokinetic torque converters and which can bereadily set up or designed to ensure adequate withdrawal of excess heatat a rate which varies or which can vary proportionally with variationsof the quantities of surplus heat.

A further object of our invention is to provide a novel and improvedmethod of removing heat from the bypass clutch of a hydrokinetic torqueconverter in such a way that the presently preferred construction and/ormode of operation of the bypass clutch can remain at least substantiallyunchanged.

An additional object of the invention is to provide a novel and improvedbypass clutch for use in hydrokinetic torque converters.

Still another object of the invention is to provide a torque converterwherein the parts of the bypass clutch and the hydraulic fluid can beshielded from overheating even though the connections to the source(s)of hydraulic fluid and the paths for the flow of fluid into, within andfrom the housing of the torque converter remain at least substantiallyunchanged.

A further object of the instant invention is to provide the hydrokinetictorque converter with a cooling system which is or which can be set upto be effective only when a withdrawal of heat from the bypass clutchand/or from hydraulic fluid is advisable or actually necessary.

Another object of the invention is to provide a cooling system which canbe installed in or incorporated into existing torque converters in sucha way that it adds little, if anything, to the space requirements asseen in the radial and/or in the axial direction of the torqueconverters.

An additional object of the invention is to provide novel and improvedfriction linings for use in the bypass clutches of hydrokinetic torqueconverters, e.g., for utilization in the power trains of motor vehicles.

Still another object of the invention is to provide novel and improvedfluid agitating devices for use in a torque converter wherein the bypassclutch is designed to operate with slip.

A further object of the invention is to provide a novel and improvedfluid flow regulating arrangement which embodies or forms part of theaforementioned cooling system and can be incorporated into existingtypes of hydrokinetic torque converters using bypass clutches whichoperate in a manner necessarily involving the generation of substantialquantities of friction heat.

SUMMARY OF THE INVENTION

One feature of the present invention resides in the provision of ahydrokinetic torque converter which comprises a housing rotatable abouta predetermined axis, a pump which is rotatable by the housing about thepredetermined axis and can be of one piece with the housing, a turbinewhich is rotatable in the housing about the predetermined axis by thepump (actually by the supply of fluid which is circulated in the housingby the pump when the torque converter is in use), means for rotating thehousing (such means can include a camshaft or a crankshaft receivingtorque from a prime mover such as a combustion engine, an electricmotor, a gas turbine, or a hybrid prime mover in the power train of amotor vehicle), an output element (such as the input shaft of thechange-speed transmission in the power train of a motor vehicle) whichis rotatable about the predetermined axis and is arranged to receivetorque from the turbine, and a fluid-operated bypass clutch which isdisposed in the housing. and is arranged to transmit variable torquebetween the housing and the output element. The clutch includes adriving component rotatable with the housing and a driven componentrotatable with the output element and movable axially of the housinginto and from frictional engagement—with and without slip—with theaforesaid driving component. The improved torque converter furthercomprises means for moving the driven component relative to the drivingcomponent in the axial direction of the housing (such moving meanscomprises first and second plenum chambers containing bodies ofhydraulic fluid at variable pressure with the provision for fluid flowbetween the chambers through the clutch), and means for regulating thefluid flow between the chambers in dependency upon the magnitude oftorque being transmitted by the clutch when the latter is at leastpartially engaged.

The regulating means preferably comprises means for automaticallyaltering the rate of fluid flow between the plenum chambers in responseto variations of the slip between the driving and driven components.

The regulating means can also comprise at least one channel (such as arecess or groove or the like) which is provided in at least one of thedriving and driven components and is arranged to establish a path forthe flow of fluid between the plenum chambers when the clutch isoperated with slip.

The regulating means is designed to increase the rate of fluid flowbetween the chambers in response to increasing slip of the driving anddriven components relative to each other.

The regulating means can include means for regulating the rate of fluidflow between the plenum chambers in dependency upon changes of RPMbetween the means for rotating the housing and the output element.

The torque converter can further comprise means for varying the pressureof fluid in at least one of the plenum chambers independently of theregulating means. Such varying means is or can be operative to vary thepressure of fluid in the at least one chamber as a function of changesof the RPM of the means for rotating the housing.

The viscosity of fluid in the flow between the plenum chambers varies inresponse to the changes of the extent of slip between the driving anddriven components, and the rate of fluid flow between the plenumchambers can be regulated in response to variations of the viscosity offluid.

As a rule, the temperature of fluid in the flow between the plenumchambers varies in response to changes of the extent of slip between thedriving and driven components, and the regulating means can change therate of fluid flow in dependency on such temperature changes.

The regulating means can be provided with at least one channel which ismachined or otherwise provided in at least one of the driving and drivencomponents to establish a path for the flow of fluid between thechambers when the clutch is operated with slip, and such regulatingmeans can comprise an adjustable barrier which determines the rate offluid flow in the at least one channel.

The driven component can comprise a piston and at least one of thedriving and driven components can comprise a friction lining whichcontacts the other component in the engaged condition of the clutch. Thedriving component can form part of or can be affixed to the housing andthe piston can be non-rotatably but axially movably mounted on theturbine or on the output element of the torque converter. Such pistoncan be arranged to at least partially seal the plenum chambers from eachother, at least while the driven component frictionally engages thedriving component.

It is also possible to provide each of the driving and driven componentswith a friction lining, and such friction linings can be and normallyare mounted in such a way that they contact each other in the partly orfully engaged condition of the bypass clutch.

The bypass clutch can be constructed in such a way that the drivingcomponent forms part of the torque converter housing and that the drivencomponent comprises a piston which at least partially seals the plenumchambers from each other in the engaged condition of the bypass clutch.

The bypass clutch can further comprise a preferably resilient frictionlamella which is disposed between the driving and driven components andis movable axially of the torque converter housing, in response to axialmovement of the driven component, to a position of frictional engagementwith the two components in the partly or fully engaged condition of thebypass clutch. The driven component can comprise a piston which isrotatable with the housing, and such clutch preferably further comprisesat least one friction lining which is or can be provided on the lamellaand frictionally engages one of the driving and driven components in theengaged condition of the bypass clutch. The arrangement can be such thatthe clutch further comprises a first friction lining which is carried bythe lamella or by the driving component and engages the drivingcomponent or the lamella in the engaged condition of the clutch, and asecond friction lining which is carried by the lamella or the drivencomponent and engages the driven component or the lamella in the engagedcondition of the clutch. Alternatively the just described embodiment ofthe clutch can comprise at least one friction lining which is providedon the driving or driven component and frictionally engages the lamellain the fully or partly engaged condition of the clutch.

The torque converter or the regulating means can comprise one or morecooling units for the bypass clutch; such cooling unit(s) can be set upto exchange heat with the driving and/or with the driven component.

In accordance with another presently preferred embodiment, the bypassclutch further comprises at least one friction lining which is borne byone of the driving and driven components and frictionally engages theother component in the partly or fully engaged condition of the clutch.The driving and driven components and the at least one friction liningare provided with friction surfaces each of which engages another of thesurfaces at least in the engaged condition of the clutch, and theregulating means of the torque converter embodying the just describedbypass clutch can be provided with recesses which extend at leastsubstantially radially of the housing axis and are machined, impressedor otherwise provided in at least one of the surfaces to establish atleast a portion of the fluid flow in the engaged condition of the bypassclutch. For example, the recesses can be provided in the surface of thedriving and/or driven component and can be embossed into the respectivefriction surface. Alternatively, the recesses can be formed bydisplacing some material of the driving and/or driven component and/orfriction lining, e.g., by impressing grooves into one side of thefriction lining to thus develop raised portions at the other side of thefriction lining; the grooves at the one side of the friction lining canconstitute a set of recesses, and the depressions between the raisedportions can serve as another set of recesses.

The friction lining can resemble a washer and, if the recesses areprovided in the surface of at least one of the driving and drivencomponents, such recesses can extend radially of the axis of the torqueconverter housing and the lengths of at least some of such radiallyextending recesses can exceed the radial width of the friction lining;the latter overlies only portions of such recesses in the engagedcondition of the bypass clutch.

The recessed surface (or each recessed surface) can be provided with anannular array of between about 8 or 10 and 400 recesses, preferablybetween about 100 and 300 recesses. The lengths of such radiallyextending recesses can be in the range of between 10 and 50 mm,preferably between 10 and 30 mm, and their depths can be less than 0.3mm, preferably less than 0.15 mm. The widths of at least some of therecesses can be in the range of between 0.2 and 20 mm, preferablybetween 0.1 and 1 mm.

The ratio of the area taken up by the recesses to the area of thenon-recessed portion of the at least one surface can be within the rangeof between about 2:1 and 1:200, preferably between about 1:1 and 1:10.Otherwise stated, if the recessed surface is to engage a flat surface,between 33% and 95% (preferably between 50% and 91%) of the flat surfaceare in actual contact with the recessed surface. At least some of theedges of the recessed surface bounding the recesses can be chamfered orbevelled (e.g., rounded).

If the bypass clutch employs a friction lamella which is disposedbetween the driving and driven components, the recesses can be providedin one or both surfaces of the lamella, i.e., i.e., in the surfaceconfronting the driving component and/or in the surface confronting thedriven component. Such recesses form part of the regulating means inthat they establish paths for the flow of fluid between the plenumchambers in the partly or fully engaged condition of the clutch. Eachcomponent, or at least that component which faces a single recessedsurface of the lamella, can be provided with a friction lining whichengages the recessed surface in the engaged or partly engaged conditionof the bypass clutch. The recesses in one or both surfaces of thelamella can include first recesses which are open inwardly toward theaxis of the torque converter housing and second recesses which are openoutwardly away from such axis. Individual second recesses or groups ofsecond recesses can alternate with individual first recesses or groupsof first recesses, as seen in the circumferential direction of thepreferably annular recessed surface or surfaces. At least some of therecesses extend or can extend at least substantially radially of theaxis of the torque converter housing.

The torque converter can further comprise a damper which is set up todamp torsional vibrations between the housing of the torque converterand the output element in the engaged condition of the bypass clutch.The damper can be designed to comprise an input having a lamelladisposed between and frictionally engaging the driving and drivencomponents in the engaged condition of the clutch, an output arranged torotate with the output element of the torque converter, and at least oneenergy storing device (e.g., at least one coil spring or a suitablyconfigurated and dimensioned block of rubber or the like) which isinterposed between the input and the output to offer a desiredresistance to turning of the input and output relative to each other.

The clutch or the regulating means can further comprise at least oneporous (i.e., foraminous or permeable) layer which is disposed betweenthe driving and driven components and establishes a plurality of pathsfor the flow of hydraulic fluid between the plenum chambers in theengaged condition of the bypass clutch. The porous layer can include orconstitute an annular disc which contains a sintered material and/oranother material that exhibits adequate porosity and can standmechanical and/or thermal stresses developing in a hydrokinetic torqueconverter. For example, the porous layer can consist of sintered metal,plastic, glass, a suitable ceramic substance or. a mixture or compoundof the above enumerated materials. The clutch utilizing the porous layercan further employ a friction lining which is interposed between thedriving and driven components; the porous layer can be force-lockinglyconnected with the driving component, driven component or frictionlining.

If the bypass clutch or the regulating means comprises a frictionlamella which is disposed between the driving and driven components andis movable axially of the torque converter housing, the housing can beprovided with an internal abutment (such as a washer-like structure)which limits the movability of the lamella in one direction and thebypass clutch or the regulating means can be provided with a pistonwhich is movable axially of the housing, which forms part of the drivencomponent and which limits the movability of the lamella in the otherdirection (as seen axially of the housing of the torque converter). Theinternal abutment can be axially movably mounted on a portion of thetorque converter housing which surrounds the bypass clutch.

At least one of the driving and driven components can consist, at leastin part, of a porous material which is employed to establish a pluralityof paths for the flow of fluid between the plenum chambers in theengaged condition of the bypass clutch. The other component of suchclutch can include a friction lining which abuts the one component inthe partially or fully engaged condition of the bypass clutch. Forexample, a porous member can be riveted to the driving or to the drivencomponent to provide a plurality of paths for the flow of fluid betweenthe plenum chambers in the engaged condition of the clutch.

The regulating means can comprise at least one array of recessesprovided in the driving and/or driven component and communicating withone of the plenum chambers, and ports provided in the recessed componentand communicating (a) with the recesses and (b) with the other plenumchamber. The recessed component can include at least one friction liningwhich confronts the other component and is actually provided with therecesses; such recessed component can further comprise a piston whichcarries the friction lining and is provided with the aforementionedports.

The recesses can be provided with open ends which communicate with theone plenum chamber, and the ports are or can be located radiallyoutwardly of the open ends of the recesses (it is assumed here that therecesses extend radially outwardly from their respective open ends). Thecomponent which is provided with recesses is or can be the drivingcomponent and can include a friction lining which is actually providedwith recesses; the driven component of such bypass clutch can include apiston actually provided with the ports which are distributed in such away that they repeatedly communicate with the recesses during operationof the clutch with slip. The arrangement can be such that the portsrepeatedly communicate with the recesses only when the clutch isoperated with slip. The number of the ports can be different from thenumber of the recesses, and the regulating means can further compriseopen-and-shut valves for the ports.

In accordance with a presently preferred embodiment, each valvecomprises a tongue or flap which is movably carried by the at least onecomponent. It is preferred to employ resilient tongues which tend toassume positions in which they permit hydraulic fluid to flow betweenthe respective recesses and the other plenum chamber. The tongues can bearranged to seal the respective recesses from the other chamber inresponse to changes of fluid pressure in the other plenum chamberrelative to the fluid pressure in the one chamber. The arrangement ispreferably such that the valves open in response to rotation of thedriving and driven components relative to each other. The recesses ofthe at least one array have open ends which communicate with the onechamber and the regulating means can further comprise an annular secondarray of recesses which are provided in the at least one component toalternate with the recesses of the at least one array. The recesses ofthe second array have open ends communicating with the other chamber andsuch recesses repeatedly communicate with the ports while the bypassclutch operates with slip.

The regulating means can include at least one annular array of recesseswhich are provided in one of the driving and driven components andcommunicate with one of the plenum chambers, an annular array of portsprovided in the other component and repeatedly communicating withsuccessive recesses of the at least one array during operation of thebypass clutch with slip, and bellows which are borne by the othercomponent and each of which communicates with one of the ports. Thebellows are contacted by fluid in the other plenum chamber and aredeformable in response to the establishment of a sufficient differentialbetween the pressures of fluid bodies in the two plenum chambers. Thebellows are or can be resilient and are arranged to receive fluid fromthe other plenum chamber when the pressures of fluid in the two plenumchambers differ to a predetermined extent. One of the driving and drivencomponents, preferably only the other component, can be provided with afriction lining. The preferably elastic bellows can consist, at least inpart, of thin sheet metal or rubber, and the fluid receiving capacitiesof such bellows are preferably limited. It is often advisable to arrangea relatively large number of bellows in a circle; such circle cancomprise between about 3 and 36 bellows, preferably between about 9 and24 bellows. The other component of the bypass clutch can comprise apiston and the bellows can include sheet metal blanks which are at leastsubstantially sealingly affixed to the piston. It is also possible toemploy a plurality of bellows all of which form part of a single pieceof sheet-like material affixed to the other component of the bypassclutch. The bellows can be designed in such a way that they normallyoffer resistance to the inflow of fluid; the arrangement is or can besuch that the bellows are inflatable against the resistance of fluid inthe other plenum chamber. At least one of such bellows can include asheet metal member which is affixed to the other component and isarranged to move by snap action between first and second positions inwhich the fluid receiving capacity of the at least one bellowsrespectively assumes a relatively large and a relatively small value.The regulating means employing such bellows can further comprise atleast one stop which is arranged to limit the extent of movement of thesheet metal member by snap action to at least one of the first andsecond positions. Such at least one stop can be arranged to prevent amovement of the sheet metal member beyond the second position. The othercomponent of the bypass clutch in a torque converter having regulatingmeans operating with bellows can include a piston and the at least onestop can form part of such piston.

Each of the aforementioned ports is preferably arranged to admit fluidinto and to provide a path for expulsion of fluid from a discretebellows; the ports can be arranged to establish communication betweenthe interiors of the respective bellows and the other plenum chamber;the one component of the bypass clutch can include a friction lining andthe recesses can be provided in the friction lining. The recesses can beprovided with enlarged portions communicating with successive ports ofthe annular array of ports when the clutch is operated with slip. Forexample, the recesses having enlarged portions can constitutesubstantially T-shaped recesses.

In accordance with a further embodiment, the regulating means cancomprise an annular undulate surface which is provided on one of thedriving and driven components, and a sealing member having a secondsurface adjacent the undulate surface and provided on the othercomponent. These surfaces establish a plurality of paths for the flow offluid only when the bypass clutch is operated with slip. The undulatesurface can be provided on a deformable ring-shaped member of a pistonforming part of the one component. The ring-shaped member can beprovided on a radially outermost portion of the piston, i.e., on aportion which is remote from the axis of the torque converter housing.The second surface can be provided on such housing.

As already mentioned before, the regulating means can include means forpumping hydraulic fluid between the plenum chambers.

The driven component of teh bypass clutch can include a first piston andthe regulating means can comprise an auxiliary (second) piston definingwith the first piston a third chamber which communicates with the plenumchambers by way of passages-provided in at least one of the driving anddriven components.

The regulating means can comprise a cooling unit which is provided atthat side of one of the driving and driven components which faces awayfrom the other component; the cooling unit can employ a third chamberfor a supply of coolant. The two components can frictionally engage eachother at a first radial distance from the axis of the torque converterhousing in the at least partly engaged condition of the clutch, and thethird chamber can be dimensioned and configurated in such a way that itincludes a first portion at the first radial distance from the axis anda second portion at a lesser second radial distance from the axis. Suchthird chamber can be outwardly adjacent the housing of the torqueconverter; alternatively, the driven component can include a pistonlocated in the housing of the torque converter, and the third chamber isadjacent that side of such piston which faces away fro the drivingcomponent.

It is also possible to employ a cooling unit which comprises asubstantially cup-shaped enclosure for the third chamber; such enclosureis sealingly affixed to one of the driving and driven components. Theenclosure can be secured to the one component by at least one of theundertakings including welding, caulking and snap action.

The coolant can be selected from the group consisting of water and aliquefied gaseous fluid. Such coolant can be arranged to exchange heatwith at least one of the driving and driven components in accordancewith evaporation enthalpy. If the coolant is a liquid at lowertemperature, it changes its aggregate state by convection to a gaseousstate in response to heating as a result of contact with at least one ofthe driving and driven components. The change of aggregate state can beeffected under the action of centrifugal force when the driving anddriven components rotate and the clutch operates with slip.

In accordance with a presently preferred embodiment, the cooling unit isconstructed in the following way: The driving and driven components ofthe bypass clutch frictionally engage each other at a first radialdistance from the axis of the torque converter housing in at leastpartly engaged condition of the clutch. The third chamber (i.e., thechamber for the supply of coolant) includes a first portion at the firstradial distance from the axis and a second portion at a lesser secondradial distance from the axis. The coolant is a liquid which at leastpartially fills the first portion of the third chamber and assumes agaseous aggregate sate in the second portion of the third chamber with atendency to become a liquid and to flow back to the first portion of thethird chamber under the action of centrifugal force in response tocooling of the gaseous phase in the second portion of the third chamber.

In addition to or in lieu of the already described undertakingsinvolving the enhancement of exchange of heat between the fluid fillingthe plenum chambers and the fluid flowing between such chambers on theone hand, and the adjacent structural elements of the torque converterand its bypass clutch on the other hand, it is possible to simplyagitate the fluid within the housing of the torque converter. To thisend, the regulating means can comprise at least one blade or vane(hereinafter called blade) which is provided on the turbine and ispreferably adjacent one of the driving and driven components of thebypass clutch (particularly the driven component) to agitate some of thefluid in the housing of the torque converter. The at least one blade isor can be affixed (such as welded, glued or riveted) to or can be of onepiece with the turbine. It is also possible to make the at least oneblade of one piece with one of the customary vanes provided at that sideof the turbine which confronts the vanes of the pump forming part of thetorque converter. For example, each vane of the turbine can be of onepiece with one of the blades. If the bypass clutch comprises one or morefriction linings, the blade or blades of the turbine can be adjacent thesingle friction lining or one of several friction linings.

It is often advisable to provide the turbine with an anular array ofpreferably equidistant blades. Such array of blades can be mounted on orcan form part of an annular carrier which is affixed to the turbine.

If the regulating means of the improved torque converter comprises atleast one pumping device, such device can be arranged to convey fluidfrom one of the plenum chambers into the other plenum chamber and/or toconvey fresh fluid from a source into one or both plenum chambers and/orto enhance the flow of fluid from one or both plenum chambers when thebypass clutch is operated with slip. In accordance with one presentlypreferred embodiment, the at least one pumping device comprises a pumpbody having first and second openings which respectively communicatewith a source of fresh or recycled fluid and with one of the plenumchambers, and a spherical or otherwise configurated pumping elementwhich is reciprocable in the pump body to effect a transfer of fluidfrom the source to the one chamber. The at least one pumping device canbe installed in or on a hub which surrounds the output element (such asthe input shaft of the change-speed transmission) of the torqueconverter. The pumping element seals one of the two openings in the pumpbody when the bypass clutch is operated without slip. At least one ofthe driving and driven components can include a friction lining which isremote from the axis of the torque converter housing, and the at leastone pumping device can be installed in the housing in such a way hat itis adjacent the friction lining. Furthermore, the at least one pumpingdevice can be arranged to communicate with at least one of the plenumchambers by way of recesses provided in one of the driving and drivencomponents. These recesses can have open ends which communicate with theone plenum chamber of the torque converter, and such regulating meanscan include additional recesses which are sealed from the one plenumchamber. The recesses can be provided in the one or in the only frictionlining of the bypass clutch.

The regulating means can comprise an annular array of pumping deviceswhich are or which can be equidistant from each other and which are orcan be identical.

Another feature of the present invention resides in the provision of ahydrokinetic torque converter which comprises a housing rotatable abouta predetermined axis, a pump which is rotatable by the housing aboutsuch axis, a turbine which is rotatable in the housing about thelatter's axis by as well as relative to the pump, means for rotating thehousing, an output element which is rotatable about the axis of thehousing and is arranged to receive torque from the turbine, and afluid-operated bypass clutch which is arranged to transmit variabletorque between the housing and the output element independently of theturbine. The clutch includes a first part which is rotatable with thehousing, a second part which is rotatable with the output element, andfriction generating means operable to transmit torque between the firstand second parts with and without slip with attendant generation offriction heat during operation with slip. The torque converter furthercomprises first and second plenum chambers which contain bodies ofhydraulic fluid at variable pressure with the provision for fluid flowbetween the plenum chambers past the friction generating means, andmeans for regulating the fluid flow in dependency upon the magnitude oftorque being transmitted by the clutch.

The just discussed torque converter can further comprise torsionalvibration damping means operating between the first part of the bypassclutch and at least one of the second part of the friction clutch, theturbine and the output element. Such torque converter can furthercomprise a stator which is provided in the housing intermediate the pumpand the turbine.

A further feature of our invention resides in the provision of ahydrokinetic torque converter which comprises a housing rotatable abouta predetermined axis, a pump rotatable by the housing about such axis, aturbine rotatable in the housing by and relative to the pump, means forrotating the housing, an output element which is rotatable about theaxis of the torque converter housing and is arranged to receive torquefrom the turbine, and a fluid-operated bypass clutch which is arrangedto transmit variable torque between the housing and the output element.The pump comprises a driving component rotatable with the housing and adriven component including a piston rotatable with the output elementand movable in the housing axially into and from frictionalengagementt—with and without slip—with the driving component, and thetorque converter further comprises means for moving the piston includingfirst and second plenum chambers in the housing, means for supplying tothe plenum chambers hydraulic fluid at variable pressure with theprovision for fluid flow between the chambers through the clutch, andadjustable means for regulating the fluid flow between the chambers independency upon the magnitude of torque being transmitted by the clutch.Such adjustable regulating means is or can be adjacent at least one ofthe driving and driven components of the bypass clutch.

Still another feature of the present invention resides in the provisionof a method of cooling an engageable and disengageable bypass clutchwhich is installed in the rotary housing of a hydrokinetic torqueconverter and has coaxial rotary driving and driven components whichfrictionally engage each other when the clutch is at least partlyengaged. The partial engagement involves (i.e., results in) a slip ofthe components of the bypass clutch relative to each other. The methodcomprises the steps of providing in the housing first and second plenumchambers and maintaining in the plenum chambers bodies of hydraulicfluid arranged to at least partly engage the clutch in response to theestablishment of adequate pressure differential between the two bodiesof fluid, establishing at least one path for the flow of fluid betweenthe plenum chambers by way of the clutch, at least in the partly engagedcondition of the clutch, and regulating the flow of fluid along the atleast one path in dependency upon (i.e., as a function of) the extent ofslip between the driving and driven components.

The regulating step can include increasing the rate of fluid flow alongthe at least one path when the clutch operates with slip and reducingsuch rate when the clutch operates without slip.

The regulating step can also include interrupting the flow of fluidalong the at least one path when the clutch is operated without slip,i.e., when the generation of friction heat is reduced to zero.

The regulating step can include installing an adjustable valve in the atleast one path.

The step of establishing the aforementioned at least one path caninclude providing the driving and driven components of the clutch withpluralities of first and second passages (such as channels, recesses,grooves or the like) for the flow of fluid to and from the first andsecond plenum chambers, and the regulating step of such method caninclude establishing communication between the first and second passagesat a frequency which increases in response to increasing slip of thedriving and driven components of the bypass clutch relative to eachother.

The regulating step can include pumping the fluid along the at least onepath at a rate which increases in response to increasing slip of thedriving and driven components of the bypass clutch relative to eachother.

Still further, the regulating step can include continuously contactingat least one of the driving and driven components of the bypass clutchwith a confined supply of coolant which changes its aggregate state inresponse to changes of temperature of the at least one component of thebypass clutch.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved hydrokinetic torque converter itself, however, both as to itsconstruction and modes of assembling, installing and operating the same,together with numerous additional important and advantageous featuresand attributes thereof, will be best understood upon perusal of thefollowing detailed description of certain presently preferred specificembodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a power train which serves to transmittorque from a prime mover to the wheels of a motor vehicle and employs ahydrokinetic torque converter embodying a bypass clutch which can becooled in accordance with the present invention;

FIG. 2 is an axial sectional view of a hydrokinetic torque converterwith a bypass clutch which is cooled by a system or unit embodying afirst form of the present invention;

FIG. 3 is a similar axial sectional view of a hydrokinetic torqueconverter constituting a first modification of the apparatus shown inFIG. 2;

FIG. 4 is an axial sectional view of a hydrokinetic torque converterwhich constitutes a second modification of the apparatus shown in FIG.2;

FIG. 5 is a fragmentary axial sectional view of a further torqueconverter;

FIG. 6 is a similar fragmentary axial sectional view of a torqueconverter constituting a modification of the apparatus shown in FIG. 5;

FIG. 7 is an axial sectional view of a further torque converter;

FIG. 8 is a similar axial sectional view of an additional hydrokinetictorque converter;

FIG. 9 is a fragmentary axial sectional view of a novel bypass clutchwhich can be utilized in torque converters and includes a speciallydesigned portion of the converter housing;

FIG. 10 is a similar fragmentary axial sectional view of a bypass clutchconstituting a first modification of the bypass clutch shown in FIG. 9;

FIG. 11 is a similar fragmentary axial sectional view of a bypass clutchconstituting a second modification of the clutch shown in FIG. 9;

FIG. 12 is a similar axial sectional view of a bypass clutchconstituting a third modification of the clutch shown in FIG. 9;

FIG. 13 is a smaller-scale elevational view of a portion of ahydrokinetic torque converter as seen from the right-hand side of FIG. 9and illustrates the distribution of fluid conveying radial recesses orchannels in the housing of the torque converter;

FIG. 13 a is an enlarged fragmentary sectional view substantially asseen in the direction of arrows from the line XIIIa—XIIIa shown in FIG.13;

FIG. 14 is a fragmentary elevational view of the piston of a bypassclutch wherein the radially outermost portion of the piston carries anannular array of inflatable and deflatable bellows forming part of thecooling system;

FIG. 15 is an axial sectional view of the piston as seen in thedirection of arrows from the line XV—XV shown in FIG. 14;

FIG. 16 a is a fragmentary axial sectional view of a bypass clutch whichcan utilize a piston with bellows of the type shown in FIGS. 14 and 15,the bellows being shown in deflated condition;

FIG. 16 b shows the structure of FIGS. 16 a but with the bellowsinflated;

FIG. 17 a is a fragmentary axial sectional view similar to that of FIG.16 a but employing a housing of the type shown in FIGS. 9, 13 and 13 a,the bellows being shown in inflated condition;

FIG. 17 b shows the structure of FIG. 17 a but with the bellowsdeflated;

FIG. 18 a is a view similar to that of FIG. 16 b or 17 a but showing afurther bypass clutch;

FIG. 18 b shows the structure of FIG. 18 a but with the bellowsdeflated;

FIG. 19 a is a fragmentary axial sectional view of a bypass clutchsimilar to that shown in FIG. 3 but employing bellows one of which isshown in deflated condition;

FIG. 19 b shows the structure of FIG. 19 a but with the bellowsdeflated;

FIG. 20 a is a fragmentary axial sectional view of a bypass clutchconstituting a modification of the clutch shown in FIGS. 19 a and 19 b,with the bellows inflated;

FIG. 20 b shows the bypass clutch of FIG. 20 a but with the bellowsdeflated;

FIG. 21 is a fragmentary axial sectional view of a bypass clutchconstituting a further modification of the bypass clutch in the torqueconverter of FIG. 3;

FIG. 22 is an enlarged fragmentary sectional view as seen in thedirection of arrows from line XXII—XXII shown in FIG. 21;

FIG. 23 is a fragmentary axial sectional view of a bypass clutchconstituting a modification of that shown in FIG. 12;

FIG. 24 is a similar fragmentary axial sectional view of a bypass clutchconstituting a modification of those shown in FIGS. 12 and 23;

FIG. 25 is a fragmentary axial sectional view of a bypass clutchconstituting a modification of that shown in the torque converter ofFIG. 8;

FIG. 26 is an enlarged view of the detail within the phantom-line circleY shown in FIG. 25;

FIG. 27 is a view as seen in the direction of arrow X shown in FIG. 26;

FIG. 28 is a view as seen in the direction of arrow W shown in FIG. 25;

FIGS. 29 a to 29 k are fragmentary elevational views of elevendifferently grooved or recessed friction linings which can be utilizedin several versions of bypass clutches embodying the present invention;

FIG. 30 is an axial sectional view of a torque converter embodying abypass clutch which is arranged to be cooled by a pump installed in thehub of the turbine of the torque converter;

FIG. 31 is a fragmentary elevational view of a bypass clutch wherein thecooling system employs an array of pumps mounted on the radiallyoutermost portion of the piston of the bypass clutch;

FIG. 32 a is an enlarged sectional view substantially as seen in thedirection of arrows from the line XXXIIa—XXXIIa shown in FIG. 31;

FIG. 32 b is a sectional view similar to that of FIG. 32 a but showingthe pumping element of the illustrated pump of the cooling system in adifferent position relative to the pump housing;

FIG. 33 is a fragmentary axial sectional view of a torque converteremploying a further embodiment of cooling means for the component partsof the bypass clutch and for the fluid;

FIG. 34 a is an enlarged fragmentary sectional view of the bypass clutchas seen in the direction of arrows from the line XXXIVa—XXXIVa shown inFIG. 33, the cooling system being operative to withdraw heat from thepartly engaged bypass clutch;

FIG. 34 b illustrates the structure of FIG. 34 a but with a sealingelement of the bypass clutch in a position in which the cooling unit forthe bypass clutch is idle; and

FIG. 35 is a fragmentary axial sectional view of a torque converter witha bypass clutch which is cooled by a fluid that changes its aggregatestate in response to heating or cooling.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to FIG. 1, there is shown a hydrokinetic torqueconverter 1 having a housing 4 a rotatable about a predetermined axis(see the axis X—X shown in FIG. 2) by a prime mover 2. The latter canconstitute an internal combustion engine of the type employed in motorvehicles, an electric motor, a gas turbine or a hybrid drive means. Theoutput shaft 3 of the prime mover 2 can be fixedly of force-lockinglyconnected with a portion 4 of the housing 4 a in any one of a number ofdifferent ways. The portion 4 which is shown in FIG. 1 is a flexibleannular metallic washer-like wall which drives the other part or partsof the housing 4 a and also a rotary pump 5 of the torque converter 1. Aturbine 6 of the torque converter is coaxial with and is normallyrotated or can be rotated by the pump 5 by way of a body of hydraulicfluid in the housing 4 a. FIG. 1 further shows a stator 10 whichconstitutes an optional part of the torque converter 1.

The output element 7 of the torque converter 1 shown in FIG. 1 is theinput shaft of a change-speed transmission 8 which can transmit torqueto one or more wheels 9 of a motor vehicle by way of a differential andone or more wheel axles. in a manner well known in the art and notforming part of the present invention. Reference may be had, forexample, to commonly owned U.S. Pat. No. 5,501,309 granted Mar. 26, 1996to Walth et al. for “HYDROKINETIC TORQUE CONVERTER WITH LOCKUP CLUTCH”,U.S. Pat. No. 5,674,155 granted Oct. 7, 1997 to Otto et al. for “METHODOF AND APPARATUS FOR TRANSMITTING TORQUE IN THE POWER TRAINS OF MOTORVEHICLES”, U.S. Pat. No. 5,738,198 granted Apr. 14, 1998 to Walth et al.for “FRICTION ELEMENT FOR USE IN CLUTCHES”, and U.S. Pat. No. 5,782,327granted Jul. 21, 1998 to Otto et al. for “HYDROKINETIC TORQUE CONVERTERAND LOCKUP CLUTCH THEREFOR”.

The transmission 8 can constitute a manual or automatic transmission ora continuously variable transmission (CVT) with an endless link chainand adjustable pulleys.

Though the stator 10 is optional, it is often desirable and necessary,e.g., to vary the torque within certain RPM ranges. In the embodiment ofFIG. 1, the stator is mounted on a fixed part 12 (such as an axiallyexpanded tubular part of the housing or case of the transmission 8) byway of a freewheel 11.

A so-called bypass or lockup clutch 13 is provided to bypass the pump 5and to establish a driving connection between the output element 3 ofthe prime mover 2 (and more specifically the wall 4) and the turbine 6.The illustrated clutch 13 comprises an axially reciprocable member 16here shown as a piston which can be moved toward and away from the wall4. The wall 4 carries an annular driving component 14, and the piston 16carries an annular driven component 15 of an adjustable frictiongenerating device 21 of the clutch 13. At least one of the components14, 15 can be provided with a friction lining of the type customarilyemployed in the friction clutches of the power trains in motor vehicles;such friction lining can be moved into sliding or non-sliding frictionalengagement with a friction lining or a metallic or other suitable memberon the other of the components 14 and 15. Such member can be providedwith a smooth, roughened and/or otherwise treated surface which canengage the friction lining when the device 21 is to transmit torquebetween the wall 4 and the piston 16; this piston can transmit torquedirectly to the input shaft 7 of the transmission 8 or indirectly by wayof the turbine 6. That torque which is actually transmitted by theclutch 13 can be a mere fraction of the torque which the wall 4 cantransmit to the piston 16 when the frictional engagement between thecomponents 14, 15 is at least substantially free of slip.

The piston 16 is mounted on a hub (corresponding to the hub 106 a shownin FIG. 2) which is non-rotatably mounted on the shaft 7 and can alsosupport the turbine 6. The connection between the piston 16 and theshaft 7 includes a first torsional vibration damper 23, and theconnection between the turbine 6 and the shaft 7 includes a secondtorsional vibration damper 24.

The magnitude of torque which is being or which is to be transmitted bythe bypass clutch 13 can be regulated by selecting the pressures ofbodies of hydraulic fluid confined in or flowing through two chambers17, 18 defined by the housing 4 a of the torque converter 1. Thepressure of fluid entering the chamber 18 by way of a conduit 19 a isdetermined by a fluid conveying pump 19 having an intake arranged todraw fluid (such as oil or transmission fluid) from a sump 20 a oranother suitable source. A pressure limiting relief valve 19 c is or canbe installed in the conduit 19 a. A further conduit 19 b serves toconvey fluid from the chamber 17 into a reservoir 20, e.g., a sump 20.

When the fluid pressure in. the chamber 18 exceeds that in the chamber17, the piston 16 is moved or urged to the left, as viewed in FIG. 1, sothat the component 15 bears upon the component 14 with a force which isproportional to the pressure differential and the wall 4 drives thepiston 16 (and hence the turbine 6 and the input shaft 7) with orwithout slip.

When the pressure differential between the bodies of fluid filling thechambers 17, 18 decreases to a predetermined value, one or more springsor other biasing means (not shown) are free to disengage the component15 from the component 14, i.e., to disengage the bypass clutch 13. It isalso possible to employ a throttle 19 d or any other suitable flowrestrictor (shown schematically in FIG. 1) in the conduit 19 b topredetermine the circumstances under which the bypass clutch 13 ispermitted or caused to open so that, from there on, the input shaft 7can be driven by the wall 4 through the medium of the pump 5, the bodyof fluid which orbits the vanes of the turbine 6 in response to orbitingof vanes forming part of the pump 5, and the torsional vibration damper24.

The sumps 20, 20 a can form parts of a single sump, they can constitutetwo discrete identical or different sumps, or they can be connected toeach other by one or more conduits 20 b which preferably contain one ormore fluid cooling units 20 c serving to ensure that the inlet of thepump 19 receives a flow of fluid having a temperature not exceeding apreselected maximum permissible value.

The structure which is shown schematically in FIG. 1 can be modified ina number of ways without departing from the spirit of this invention.For example, the pump 19 can be installed in the conduit 19 b to drawfluid from the sump 20 and to convey such fluid into the chamber 17whence the fluid flows (when necessary or desired) into the chamber 18,conduit 19 a and sump 20 a.

The chambers 17, 18 are sealed from each other in such a way that, whendesired or necessary, they can communicate only by way of the bypassclutch 13 (and more specifically by way of the friction generatingdevice 21 including the components 14 and 15).

In accordance with a feature of the present invention, the frictiongenerating device 21 is constructed and assembled and operates in such away that the components 14, 15 can regulate the flow of fluid betweenthe chambers 17, 18, i.e., that there exists a fluid flow regulating orlimiting arrangement 22 which conforms the rate of fluid flow to themomentary requirements, i.e., to the desired or required extent offrictional engagement between the components 14 and 15. The arrangement22 conforms the extent of fluid flow into and from the chambers 17, 18to the required or desired or necessary extent of frictional engagementbetween the components 14 and 15.

The requirements can be such that there normally exists an at leastsmall (such as negligible) rate of flow of pressurized fluid involving anegligible angular displacement of the driving means (including the wall4) and the driven means (including the input shaft 7) relative to eachother, and/or a rate of flow which varies in dependency upon a slipparameter; the operation of the flow regulating arrangement 22 can becontrolled in dependency upon (a) the RPMs of the wall 4 and shaft 7,(b) the differential between the pressures of fluid bodies in thechambers 17, 18, (c) the viscosity of the fluid, and/or (d) anevaluation of the just enumerated parameters (a) to (c). It is importantand highly desirable, as well as practical for normal use of the torqueconverter 1, that the operation of the regulating arrangement 22 takeplace automatically within the torque converter. The means for effectingsuch automatic operation of the arrangement 22 can include or resemblethe driving and driven components 14, 15 and/or means for metering theflow of fluid through these components.

The slip-dependent regulation or control of the flow of hydraulic fluidexhibits the important advantage that, when the rate of fluid flowincreases in response to an increasing difference between the RPMs ofthe wall 4 and the shaft 7, the components 14, 15 (which generate alarger quantity of heat if the aforementioned difference between theRPMs increases while the components are in frictional engagement witheach other) undergo a more pronounced cooling action because the rate offluid flow from one of the chambers 17, 18, through the device 21including the components 14, 15, and into the other chamber is morepronounced. Otherwise stated, the temperature of fluid flowing betweenthe chambers 17, 18 via flow regulating arrangement 22 is lower if thespeed of fluid flow is higher.

A less pronounced heating of the components 14, 15 is desirable andadvantageous because it involves a lesser wear upon the device 21 andalso because the composition of the fluid remains unchanged (i.e.,acceptable) for a longer interval or period of time. Furthermore, adamming of the fluid by the regulating arrangement 22 in response to areduced slip exhibits the advantage that the operation of the pump 19 ismore economical because the output of the pump must be increased due tohigher losses resulting from the flow of fluid into the lower-pressurechamber (i.e., into the chamber 17 within the housing 4 a shown inFIG. 1) when the bypass clutch 13 is engaged, namely when the pumpoutput is higher because the pressure of fluid in the chamber 18 (thisentails an engagement of the bypass clutch) is raised by the pump.

The dampers 23, 24 counteract torsional vibrations; each of thesedampers can be a single-stage or a multistage damper. If the damper 23and/or 24 is a multistage damper, the individual stages can be set up tooperate in series or in parallel. The individual stops of a multistagedamper can serve to protect the elastic means between the input andoutput parts of the damper 23 and/or 24. In addition, one can providedelayed or non-delayed friction generating devices each of which issuperimposed upon a single stage or each of which acts upon severalstages.

The first damper 23 is installed in the power flow between the bypassclutch 13 and the input shaft 7 of the transmission 8, i.e., it bypassesthe turbine 6. The input of this damper is the piston 16, and its outputis the aforementioned hub which is non-rotatably but axially movablymounted on the shaft 7 (or which non-rotatably but axially movablysupports the piston 6).

The damper 24 is installed between the turbine 6 and the shaft 7. Forexample, the turbine 6 can be mounted (with limited freedom of angularmovement) on a hub which is borne by the shaft 7; the output of thedamper 24 is then non-rotatably mounted on such hub. The range of thedamper 24 (which is mounted in the just described manner) is determinedby the extent to which the turbine 6 can turn relative to the hub on theshaft 7.

It is also possible to replace the dampers 23, 24 with a single damper.For example, the input of such single damper receives torque from thepiston 16 and/or from the turbine 6, and its output is operativelyconnected with the input shaft 7 or with the hub which is non-rotatablymounted on the shaft 7.

The flow regulating or limiting arrangement 22 (or an equivalentthereof) does not constitute the only novel feature of the improvedtorque converter 1. Thus, this torque converter can be provided withauxiliary masses 25 a, 25 b, 25 c and 25 d which serve to meet (satisfy)specific requirements regarding the damping and/or absorption(elimination) of torsional vibrations. For example, one can rely on theso-called dual mass flywheel effect by installing the auxiliary masses25 b, 25 a upstream and downstream of the torsional vibration damper 23and/or by instaling the auxiliary masses 25 c, 25 d upstream anddownstream of the damper 24. The auxiliary masses (or one or more suchmasses) need not constitute separately produced parts, i.e., at leastone thereof can constitute a standard component or a group of two ormore standard components of a torque converter wherein, in addition totheir well known functions, they also serve as auxiliary massesassociated with the torque converter 23 or 24. By way of example only,one of the auxiliary masses 25 a to 25 d can constitute or form part ofthe turbine 6, of the housing 4 a, of one or more portions of thehousing 4 a and/or others, as long as the moment of inertia and/or thebulk or weight of such multiple-purpose auxiliary mass is satisfactoryfor utilization in conjunction with the damper 23 or 24.

Still further, it is within the purview of the invention to omit theauxiliary mass 25 a and/or 25 d, i.e., to utilize only the auxiliarymass(es) 25 b and/or 25 c which is or which are installed in the powerflow(s) upstream of the respective damper(s) 23 and/or 24. The singleauxiliary mass (25 b or 25 c) is preferably that mass which is moredistant from the axis of the shaft 7, i.e., which is located radiallyoutwardly of the respective torsional vibration damper 23 and/or 24.Stated otherwise, the single auxiliary mass (25 b and/or 25 c) isinstalled in the power flow upstream of the respective damper (23 and/or24); this enhances the moment of inertia.

It is advisable (and actually highly desirable and advantageous) toinstall the auxiliary mass(es) in such space or spaces which is or whichare available in a hydrokinetic torque converter; such spaces include,for example, that or those at the radially outer and/or inner torus ofthe turbine, and in a corner or region of the housing 4 a radiallyoutwardly of the piston 16.

The auxiliary mass 25 a and/or 25 d can be directly or indirectlymounted on the input(s) of the respective damper(s) 23 and/or 24, andthe mass 25 b and/or 25 c can be directly or indirectly mounted on theinput(s) of the respective damper 23 and/or 24. For example, and asactually shown in FIG. 1, the auxiliary mass 25 b is provided on orforms part of the piston 16 upstream of the damper 23 (as seen in thedirection of power flow from the bypass clutch 13 (i.e., from the wall4) to the input shaft 7. Furthermore, and as also shown in FIG. 1, theauxiliary mass 25 c is mounted on or forms part of the turbine 6, i.e.,such mass is located in the flow of power toward the input of the damper24.

FIG. 2 is an axial sectional view of a torque converter 101 which isdriven by the output shaft (such as a crankshaft) 103 of a prime mover,e,g, the engine of a motor vehicle. The shaft 103 has an axiallyextending centering projection 103 a engaging a flexible torquetransmitting member 126 which is or which can be made of a metallicsheet material and can be said to form a detachable part of a housing104 a of the torque converter 101. The means for fixedly but separablysecuring the radially innermost annular portion of the member 126 to theshaft 103 includes an annulus of threaded fasteners 103 b. Other typesof fasteners can be utilized with equal advantage.

The annular radially outermost portion of the member 126 isnon-rotatably connected with an annular starter gear 126 a in such a waythat the latter cannot move axially of the housing 104 a. Therotation-preventing connection between the starter gear 126 a and thehousing 104 a can include mating gear teeth, a caulking, a welded jointor the like. It is also possible to employ a starter gear which isshrunk onto the member 126 or onto another part of the housing 104 a.

The member 126 and/or another part of the housing 104 a can also serveto carry a set of markers or other suitable indicia which rotate withthe housing and form part of a means for regulating the operation of theprime mover. An annulus of receptacles 104 b is separably connected withthe member 126 between the annulus of fasteners 103 b and the startergear 126 a; the connection can include threaded fasteners 126 b, aself-locking device, a bayonet mount (not shown) or the like.

The receptacles 104 b can constitute circular or arcuate bodies and areaffixed to the radially outermost portions of the housing 104 a, e.g.,by welding, by rivets or the like; for example, the housing 104 a and/orthe member 126 can be provided with projections which are riveted to thereceptacles 104 b.

The housing 104 a can be axially offset at the receptacles 104 b so thatthe receptacles are axially spaced apart and provided room for thefastening of the member 126 on the crankshaft 103. To this end, theradially outer portion of the member 126 (namely the portion adjacentthe receptacles 104 b) can be configurated to extend axially of thetorque converter 101 and away from the crankshaft 103.

The receptacles 104 b are provided with circumferentially spaced-apartaxially extending lobes 104 c which are affixed to the housing 104 a. Inaddition to or in lieu of such lobes 104 c, the connection between thereceptacles 104 b and the housing 104 a can be constructed and designedin such a way that, in accordance with a desirable aspect of theinvention, it need not employ discrete fasteners (such as the lobes 104c); instead, the housing 104 a can be provided with separately producedembossed portions 104 d which together constitute a cam ring affixed tothe housing and such cam ring can be provided with teeth, profiledportions, Hirth gears or serrations and/or pins. This renders itpossible to dispense with the fastener means 126 b. Moreover, suchdesign (which can be employed with advantage in all or nearly al typesof torque converters) renders it possible to simplify the mounting ofthe torque converter 101 on the flexible torque transmitting member 126during the final stage of assembly of the power train of a motorvehicle.

The member 126 can be mounted on the housing 104 a in such a way that itstores energy and the axial torque of the torque converter is preferablyapplied in a direction toward the transmission case (not shown) ortoward the transmission input shaft 107 by way of an abutment which isor which can be mounted in a bearing. The form-locking connectionbetween the member 126 and the housing 104 a can be designed in such away that it automatically orients itself during the assembly while theconnection is being established.

It is clear that the lobes 104 c can be made of one piece with themember 126, e.g., by folding partially separated lugs of the member 126over themselves. In addition, the fasteners 126 b and/or the receptacles104 b and/or the starter gear 126 a can serve as auxiliary masses whichpositively influence the torsional vibration behavior of the power trainby resorting to the so-called dual masses effect.

It is also possible to omit the member 126 and to establish a directform-locking connection between the housing 104 a and the crankshaft103. For example, the crankshaft 103 can be made of one piece with orcan carry a hardened extension having a diameter less than that of themember 126 and being located at the same radial distance from the axisX—X as the fasteners 103 b. Such hardened extension can be affixeddirectly to a complementary portion of the housing 104 a (e.g., to astamped portion of the housing) to thus establish a form-lockingconnection. The form-locking connection can be configurated in such away that it can simultaneously compensate for an offset between thecrankshaft 103 and the transmission input shaft 107. The housing 104 acan be axially flexible between its periphery and the form-lockingconnection, e.g., by employing a sheet metal having varying thicknesssin the region of such connection.

An important advantage of the form-locking connection is to serve as anoise reducing or noise damping arrangement, and such noise-reducingeffect can be enhanced by providing the relevant parts with suitablecoatings made of one or more metals, alloys, plastics or ceramics. Stillfurther, it is possible to employ between the parts of the form-lockingconnection one or more energy storing elements in. the form of springs,inserts made of rubber and the like.

The housing 104 a and the pump 105 of the torque converter 101 areform-lockingly connected to each other, as at 105 a, to constitute theinput element of the torque converter 101. As can be seen in FIG. 2, theform-locking connection 105 a can comprise several equidistant parts(FIG. 2 shows three parts). disposed at the periphery of the pump 105and each including a male part provided on the pump 105 and extendinginto a complementary female part of the housing 104 a.

That end portion (104 e) of the housing 104 a which is remote from themember 126 (as seen in the direction of the axis X—X ) constitutes asleeve surrounding an axially projecting tubular extension 108 a of thetransmission. The extension 108 a is sealingly surrounded by the sleeve104 e and is also surrounded by the freewheel 111 for the stator 110.

The pump 105 and the turbine 106 are provided with customary vanes orblades (not shown) which cooperate to ensure that the body of hydraulicfluid in the housing 104 a rotates the turbine 106 in response torotation of the pump 105 by the crankshaft 103. The (optional) stator110 is disposed between the pump 105 and the turbine 106 (as seen in thedirection of the axis X—X) and is radially outwardly adjacent thefreewheel 111.

The turbine 106 is non-rotatably connected with a hub 106 a, e.g., by anannular array of rivets, and this hub is non-rotatably but axiallymovably affixed to the transmission input shaft 107. An annular seal 107a is interposed between the shaft 107 and the hub 106 a, and the latterabuts a thrust bearing 110 b which, in turn, abuts the stator 110.

The hub 106 a has an axial extension surrounded by the radiallyinnermost portion of the axially movable piston 116 which forms part ofthe torque converter bypass clutch 113. An annular seal 106 c isinserted between the piston 116 and the hub 106 a; the latter has adisc-shaped extension 106 b which extends radially outwardly and isriveted to the turbine 106. The extension 106 b further serves as a stopwhich determines the extent of rightward axial movement of the piston116 of the bypass clutch 113.

The piston 116 cooperates with the radial wall 104 of the housing 104 ato transmit torque from the crankshaft 103 (via wall 104) directly tothe hub 106 a (i.e., to the transmission input shaft 107), namely tobypass the pump 105 and the turbine 106, when the bypass clutch 113 isengaged (with or without slip). More specifically, the piston 116carries a friction lining 115 (or has a properly finished frictionsurface) which engages a complementary friction lining or frictionsurface 114 of the wall 104 when the clutch 113 is at least partlyengaged. If used, the friction lining or linings (such as 115 and/or114) can be glued, riveted and/or otherwise affixed to the piston 116and/or to the wall 104. Certain presently preferred embodiments of thefluid flow regulating or limiting arrangement 122 of the bypass clutch113. or an analogous bypass or lockup clutch will be described ingreater detail with reference to FIGS. 9 to 13.

The piston 116 divides a part of the interior of the housing 104 a intoplenum chambers 117, 118 which are sealed from each other (when thebypass clutch 113 is engaged, either entirely or with slip) to theextent determined by the flow regulating arrangement 122. Hydraulicfluid is admitted into the plenum chamber 118 by way of a conduit 119 awhich is defined by an annular clearance between the sleeves 104 e and108 a. A conduit 107 b which serves to permit hydraulic fluid to issuefrom the chamber 117 is a bore in the transmission input shaft 107 whichdischarges into an annular passage 119 b of the shaft 107. The sleeve108 a and the shaft 107 are sealingly engaged by a friction bearing 108b which serves as a means for sealing the passage 119 b from thesurrounding atmosphere; in addition, the combined bearing element andseal 108 b prevents the flow of hydraulic fluid from the conduit 119 ainto the chamber 118.

When the fluid pressure in the plenum chamber 118 rises above that inthe plenum chamber 117, the piston 116 is moved axially and the frictiongenerating device 121 including the frictionally engageable members 114,115 having friction surfaces 114′, 115′ establishes a frictionalengagement to transmit torque from the wall 104 of the housing 104 a tothe piston 116.

If the fluid pressure in the chamber 117 thereupon rises above that inthe chamber 118, the surfaces 114′, 115′ become separated from eachother so that the bypass clutch 113 ceases to transmit torque; thetransmission of torque from the crankshaft 103 to the transmission inputshaft 107 then takes place by way of the housing 104 a, pump 105, fluidbetween the pump 105 and the turbine 106, and the turbine hub 106 a.

When the bypass clutch 113 is fully or partly, engaged (i.e., when itoperates without slip or with some slip), the piston 116 continues totransmit at least some torque to the hub 106 a. Vibrations of suchtorque can be damped by a damper 123 which operates between the piston116 and the hub 106 a. The damper 123 includes an input member 123 awhich is non-rotatably affixed to the piston 116, and an output member123 b non-rotatably affixed to the hub 106 a. The input member 123 acomprises two discs which flank the disc-shaped output member 123 b. Thediscs of the input member 123 a are shown as being riveted to the piston116. The disc of the output member 123 b is non-rotatably but axiallymovably mounted on the hub 106 a; to this end, the member 123 b has oneor more axially parallel internal teeth mating with external teeth ofthe hub 106 a. One or more energy storing elements 123 c (one shown FIG.2) yieldably oppose angular movements of the input and output members123 a, 123 b relative to each other; to this end, the energy storingelement(s) 123 c reacts or react against one or more abutments providedon the input member 123 a and bear upon one or more abutments on theoutput member 123 b. Reference may be had, for example, to commonlyowned U.S. Pat. No. 5,860,863 granted Jan. 19, 1999 to Friedmann et al.for “APPARATUS FOR DAMPING VIBRATIONS”. The torsional vibration damper123 is further provided with suitable means for limiting the extent ofangular movability of the input and output members 123 a, 123 b relativeto each other; such limiting means can provide first and second stopswhich are respectively mounted on or made of one piece with the members123 a, 123 b.

It is further possible and often advisable to provide a slip clutch 123d which operates between the input and output members 123 a, 123 b andpermits such members to turn relative to each other only when the torquebeing transmitted by the input member 123 a rises to a predeterminedvalue. The illustrated slip clutch 123 d acts axially between themembers 123 a, 123 b and can comprise one or more energy storingdevices.

The wall 104 of the housing 104 a of the torque converter 101 carries acentering stub 104 f which extends into a recess 103 c of the crankshaft103. The stub 104 f is welded to the wall 104 and is centered thereon bya projection 104 g which is a stamped out part of the wall 104; however,it is also possible to make the stub 104 f of one piece with the wall104. The just described combined centering and torque transmitting meanscan serve to compensate for eventual angular and/or axial misalignmentsof the shaft 103 and the transmission input shaft 107 relative to eachother.

The aforementioned axial projections 103 a of the crankshaft 103 arepreferably profiled and dimensioned in such a way that they facilitatethe insertion of the stud 104 f into the opening or recess 103 c duringmounting of the torque converter 101 on the output shaft 103 of theprime mover.

The projection 104 g can further serve to facilitate accurate mounting(e.g., welding) of the stub 104 f on the wal 104, particularly toaccurately center the stud. The latter need not be a solid body but canbe replaced with a tube or sleeve. Moreover, welding of the stub 104 fto the wall 104 (as actually shown in FIG. 2) is optional, i.e., it canbe replaced by riveting or the like.

It can be said that the stub 104 f forms part of a pilot bearing whichensures simple, predictable and accurate mounting of the torqueconverter 101 on the output shaft 103 of the prime mover; such pilotbearing can be utilized with advantage in many other types of torqueconverters, clutches and the like. Furthermore, a similar or analogousor at least substantially identical pilot bearing can be utilized foraccurate and reliable mounting of the transmission input shaft 107 inthe torque converter 101 and/or in the crankshaft 103. For example, thefront end portion of the shaft 107 can be received in a sleeve-likecentral part of the housing 104 a of the torque converter 101. Thehousing 104 a can be provided with a projection similar to or analogousto the projection 104 g and extending into a sleeve-like member which,in turn, receives the front end portion of the transmission input shaft107.

FIG. 3 is an axial sectional view of a torque converter 201 whichdiffers from the torque converter 101 of FIG. 2 primarily in the designof the bypass clutch or lockup clutch 213. Thus, the radially outermostportion of the piston 216 of the clutch 213 is non-rotatably but axiallymovably secured to the radial wall 204 of the housing 204 a. A featureof the piston 216 (this feature can be embodied in the pistons of all ornearly all bypass clutches for torque converters) is that the radiallyoutermost portion of the piston carries leaf springs 216 a which areaffixed to the housing 204 a. The leaf springs 216 a are spaced apartfrom each other (as seen in the circumferential direction of the piston216), one end portion of each leaf spring 216 a is affixed to thehousing 204 a, and the other end portion of each such leaf spring issecured to the piston 216 of the bypass clutch 213. The leaf springs 216a are preferably riveted to the wall 204; to this end, the wall 204 isprovided with wart-like projections or prtuberances 204 h. However, itis also possible to provide such or similar protuberances on the piston216.

The piston 216 is turnable on a hub 206 a which surrounds the inputshaft 207 of the transmission. A thrust bearing 206 d is interposedbetween the hub 206 a and the piston 216; the illustrated bearing 206 dis a disc which is installed between a radially outwardly extendingportion of the hub 206 a and the adjacent radially extending annularportion of the piston 216.

When the bypass clutch 213 transmits torque (i.e., when the piston 216rotates with the wall 204 with or without slip), the transmission inputshaft 207 receives torque by way of the input member 223 a of thetorsional vibration damper 223 which frictionally engages the outputmember 223 b. The latter is non-rotatably but axially movably mounted onthe hub 206 a. The input member 223 a is riveted or otherwise affixed toa friction lamella 223 d the radially outermost portion of which carriestwo friction linings having friction surfaces 214 a′, 214 b′ disposedradially inwardly of the projections 204 h. The linings having thesurfaces 214 a′, 214 b′ are respectively adjacent to complementaryfriction linings having friction surfaces 215 a′, 215 b′.

The output member 223 b of the damper 223 is non-rotatably secured tothe hub 206 a by annuli of mating teeth 223 e. The reliability of suchconnection is enhanced by providing the radially innermost portion ofthe output member 223 b with a sleeve having axially parallel internalteeth in mesh with complementary teeth of the hub 206 a.

The torsional vibration damper 223 is similar to (or can be identicalwith) the damper 123 shown in FIG. 2.

The bypass clutch 213 is designed to transmit torque by way of twofriction linings, i.e., it provides a larger composite friction surfacethan the bypass clutch 113 of FIG. 2. This can be of advantage in thatthe clutch 213 is capable of transmitting larger torques or oftransmitting torques similar to those transmittable by the clutch 113but with smaller friction surfaces; the latter feature is important whenit is desirable or necessary to reduce the dimensions of the bypassclutch.

The fluid flow regulator 222 can be provided on (or can utilize) thefriction linings having the surfaces 214′, 215′ and/or 214 b′, 215 b′.Presently preferred embodiments of such regulator are depicted in FIGS.22 to 25.

FIG. 4 shows certain features of a hydrokinetic torque converter 301which is similar to the torque converter 201 of FIG. 3. The prime moverand the transmission are not shown in FIG. 4. The main differencebetween the torque converters 201 and 301 is that the latter employs adifferent bypass clutch 313 and a different torsional vibration damper323. In accordance with a feature of the invention which is embodied inthe torque converter 301, the torsional vibration damper 323 serves as aturbine damper as well as a means for damping vibrations beingtransmitted by the bypass clutch 313. To this end, the input 323 a ofthe damper 313 is non-rotatably secured to the hub 306 a for the turbine306 (this turbine is non-rotatably secured to the hub 306 a) as well asto the friction lamella (energy storing device) 323 d. Thus, the input323 a of the damper 323 can receive torque from the turbine 306 as wellas from the bypass clutch 313.

The input 323 a of the damper 323 is form-lockingly secured to the hub306 a by annuli of mating teeth 323 e, and the lamella 323 d is fixedlysecured (e.g., by rivets) to the input 323 a radially outwardly of theenergy storing elements 323 c. The hub 306 a is free to rotate relativeto the input shaft (not shown) of the transmission; to this end, adiscrete hub portion 306 f is provided with internal teeth 307 b matingwith complementary teeth of the transmission input shaft. The hub 306 ais rotatable on the discrete hub portion 306 f, preferably in a frictionbearing 306 g or on an antifriction bearing (not shown) which surroundsthe discrete hub portion 306 f.

The output 323 b of the damper 323 is fixedly secured to the discretehub portion 306 f, e.g., by welding (such as laser, impulse or spotwelding) or by caulking

In order to facilitate broaching of the teeth 307 b, there is provided adiscrete hub portion or member 306 h which can be received in the hub306 a; e.g., the hub 306 a can be a press fit on the discrete member 306h and is also mounted on the transmission input shaft. The latter can beprovided with bearings rotatably mounting the member 306 h.

Damping of torsional vibrations is effected by causing the input 323 aof the damper 323 to turn relative to the output 323 b and/or vice versaagainst the opposition of the energy storing element(s) 323 c as well asby overcoming (a) the resistance of a friction generating device 323 dbetween an axially effective energy storing element 323 b′ and the input323 a and/or (b) the friction torque of the friction bearing 306 gand/or preferably a slip clutch 323 b″. The lateral part 323 b′ isconnected with the output 323 b by an annulus of rivets 323 f′ andcooperates with the output 323 b to confine the input 323 a; theradially outer portion of the input 323 a is secured to the lamella 323d by rivets 323 f. The input 323 a is disposed between the output 323 band the lamella 323 d; these parts are provided with at least partiallyregistering windows for the energy storing element(s) 323 c each ofwhich can include a single coil spring or two or more suitablyinterfitted coil springs. The output 323 b and the lamella 323 d are orcan be provided with suitable stops (not referenced) which determine themaximum compression of the coil spring(s) and the maximum extent ofangular movability of the input 323 a and the output 323 b of thetorsional vibration damper 323 relative to each other.

FIGS. 5 and 6 respectively illustrate parts of torque converters 401 and401 a which are similar to but not identical with each other. All suchparts of these torque converters which are plainly identical with eachother are denoted by identical reference characters. The housing 404 aof each torque converter is driven by a prime mover (e.g., a combustionengine, not shown) and transmits torque to the respective pump 405. Thelatter can drive the turbine 406 which cooperates with the pump to flankan optional stator 410. The bypass clutch 413 can be engaged to transmittorque (with or without slip) from the washer-like annular part 404 i ofthe housing 404 a directly to the hub 406 a non-rotatably surroundingthe input shaft (not shown) of the change-speed transmission in thepower train of a motor vehicle. An entraining disc 416 b is riveted tothe piston 416 of the bypass clutch 413 and is axially movably butnon-rotatably mounted on the hub 406 a. The disc 416 b is provided withan annulus of axially parallel internal teeth 416 c mating withcomplementary external teeth of the hub 406 a. The connection betweenthe piston 416 and the disc 416 b comprises an annular array of rivets416 d (only one shown in each of FIGS. 4 and 5).

In accordance with a modification, the disc 416 b in each of the torqueconverters 401 and 401 a can be replaced with a torsional vibrationdamper having an input and an output which can be turned relative toeach other against the resistance of one or mote coil springs or othersuitable energy storing elements and/or against the opposition of one ormore slip clutches. The input and/or the output of the device whichreplaces the disc 416 b of the torque converter 401 or 401 a can consistof several laminations, and the input can be further affixed to theturbine 406 (in addition to or instead of the connection to the disc 416b) or to a part which shares the angular movements of the turbine.

Frictional engagement between the piston 416 (driven part) and thehousing 404 a (driving part) can be esablished by the cooperatingfriction generating members 414 and 415, and more specifically by thefriction surfaces 414′, 415′ of the respective members. The drivingmember 414 receives torque from the aforementioned washer-like portion404 i of the housing 404 a. The portion 404 i has an annular part whichis welded to the major part of the housing 404 a (namely to the partwhich carries or is of one piece with the pump 405) and extends towardthe prime mover (not shown), and a radially inwardly extending partwhich bears the member 415. The member 414 is affixed to the radiallyoutermost portion of the piston 416. At least one of the members 414,415 can constitute or comprise at least one friction lining having therespective one of the friction surfaces 414′, 415′.

The reference character 422 denotes the fluid flow regulator which, incertain parts of this specification, is denoted by the character x22wherein x denotes the respective Figure of the drawings. This regulatorcorresponds to the previously described regulators (such as theregulator 222 shown in FIG. 3). The washer-like member 404 i replacesthe walls 4, 104, 204, 304 respectively shown in FIGS. 1, 2, 3 and 4.

The mode of operation of the torque converter 401 or 401 a departs fromthat of the torque converters 1, 101, 201 and 301 in the followingrespects: In the torque converters 401 and 401 a, the pressurized fluidfirst flows into the plenum chamber 417 and the bypass clutch 413 isengaged when the pressure of fluid in the plenum chamber 417 exceedsthat of fluid in the plenum chamber 418, i.e., when the fluid begins toflow through the fluid flow regulator 422. The bypass clutch 413 beginsto transmit torque (with or without slip) when the pressure of fluid inthe plenum chamber 417 reaches a level at which the bypass clutch 413 isat least partially engaged, i.e., when the piston 416 has moved axiallytoward the turbine 406 to a position in which the friction surfaces414′, 415′ of the members 414, 415 frictionally engage each other sothat the washer-like member 404 i of the housing 404 a (which is drivenby the prime mover) begins to transmit torque to the hub 406 a (andhence to the input shaft of the transmission) by way of the members 414,415 and the piston 416.

The bypass clutch 413 remains at least partly engaged as long as thepressure of fluid in the chamber 417 at least slightly exceeds thepressure in the chamber 418. It is often desirable to employ at leastone energy storing device which automatically disengages the bypassclutch 413 as soon as the pressure of fluid in the chamber 417 begins todecrease; for example, such device can include one or more coil springsor other suitable springs which react against the hub 406 a and bearupon the piston 416 in a direction to move the piston axially to theleft, as viewed in FIGS. 5 and 6. An advantage of such energy storingdevice or devices is that they reduce the likelihood of overheating ofthe fluid (such as oil or a transission fluid) which fills the chambers417, 418 and is likely to be heated during prolonged operation of thebypass clutch 413 with slip, i.e., during that stage of operation of theclutch 413 when the fluid is caused to flow gradually through the fluidflow regulator 422 from the chamber 417 into the chamber 418. It is tobe borne in mind that, in many instances, the fluid which fills thechambers 417, 418 is circulated through the transmission and is likelyto adversely affect the heat-senstive part(s) of the transmission if itis permitted to reach an elevated temperature during flow through theregulator 422 at a rate which is customary during operation of theclutch 413 with slip. The situation is different if the fluid leavingthe chamber 418 is caused to enter an evacuating conduit which causesthe heated fluid to flow through one or more fluid cooling units (heaexchangers). Such cooling unit(s) can be dispensed with if the fluidleaving the chamber 417 is caused to mix with the body of cooler fluidin the chamber 418 prior to entering the transmission.

It is equally within the purview of the invention to convey the fluidthrough one or more cooling units prior to entry into the chamber 417,i.e., to ensure that the parts 414, 415 of the regulator 422 areinvariably contacted by a relatively cool fluid which passes-through theregulator 422 in small or relatively small quantities.

The torque converters 401, 401 a respectively comprise fluid coolingunits 427 a, 427 b of the type adapted to be utilized with advantage inthe previously described torque converters 1, 101, 201 and 301 as wellas in many other types of torque converters. The purpose of the coolingunits is to agitate the fluid in the plenum chamber 418 adjacent thewasher-like member 404 i of the housing 404 a. Such agitation takesplace as soon as or as long as the parts 406 and 404 i turn relative toeach other. Analogous results can be obtained by installing one or morecooling units in positions in which they become active as soon as thepiston and the turbine begin to perform angular movements relative toone another.

The cooling unit 427 a of FIG. 5 comprises an annular array of blades orvanes 428 a which are mounted on or form part of the turbine 406 and arearranged to orbit adjacent the member 404 i of the housing 404 a. Forexample, the blades 428 a of the cooling unit 427 a can constituteseparately produced parts which are riveted, welded and/or otherwisereliably affixed to the turbine 406. The blades 428 a of the coolingunit 427 a can also perform one or more additional functions, such as ofsecuring the customary turbine vanes 406′ to the turbine 406; the blades428 a can form suitably deformed integral lugs or analogous parts of theturbine 406.

When the cooling unit 427 a is in actual use, the blades 428 a cause thefluid which is heated in the region of the fluid flow regulator 422 toflow away from the parts 414, 415 and to intensively mix with coolerfluid in those portions of the chamber 417 which are remote from theparts 414, 415. Moreover, the blades 428 a cause the fluid (which hasbeen heated by the parts 414, 415) to exchange heat with the portion 404i of the housing 404 a. All such modes of preventing excessive localizedheating of fluid at the regulator 422 contribute to prevention ofoverheating of the fluid in the chamber 417 as well as of fluid whichissues from the chamber 417 to flow, for example, into the transmissionof the power train employing the torque converter 401.

The cooling action of the cooling unit 427 b in the torque converter 401a of FIG. 6 is analogous to that of the cooling unit 427 a in the torqueconverter 401 of FIG. 5. The difference is that the blades 428 b of thecooling unit 427 b form part of a separately produced disc-shaped member428 c which is welded to the turbine 406 and is located in the plenumchamber 418. It is clear that the blades 428 b can constitute separatelyproduced parts which are welded, riveted or otherwise affixed to themember 428 c. Again, the blades 428 b are adjacent the portion 404 i ofthe housing 404 a, i.e., next to the members 414, 415 which are a causeof heating of fluid in the chamber 418 or on its way from the chamber417 into the chamber 418.

FIG. 7 shows a torque converter 501 wherein the rotary housing 504 acomprises a hollow pin 504 f having teeth meshing with the teeth of ahollow transmission input shaft 507. The latter receives torque from theprime mover (not shown) by way of the torque converter 501. The pin 504f has an axial extension which non-rotatably but axially movablysupports an auxiliary piston 516 e having a radially outermost portionin sealing engagement with the adjacent axially extending tubular partof the housing 504 a. The thus obtained annular compartment 518 abetween the leftmost portion of the housing 504 a and the auxiliarypiston 516 e can receive fluid to effect an axial movement of theauxiliary piston in a direction to the right, as viewed in FIG. 7.

The auxiliary piston 516 a abuts the axially movable piston 516 of thebypass clutch 513. The piston 516 is mounted on an extension orprojection 506 i of a hub 506 a which is movable axially of but cannotrotate relative to the transmission input shaft 507. The piston 516constitutes or is connected with a discrete output member of the torqueconverter 501; for example, the discrete output member can be welded(such as-spot welded), riveted and/or otherwise non-rotatably affixed tothe piston 516 so that it shares all axial movements of the latter.

The driving part is constituted by a washer-like member 504 i which isnon-rotatably (such as form-lockingly) connected with the housing 504 aand is held against axial movement by an abutment or stop 504 k. Themember 504 i extends radially inwardly from the radially outer oroutermost portion of the housing 504 a. The form-locking connection isor can be established by a profiled (such as toothed) extetnal surfacewhich is provided on the member 504 i and mates with a complementary(e.g., put through) internal surface of the adjacent portion of thehousing 504 a. Frictional engagement involves a lamella 523 d by way offriction surfaces 514 a, 514 b, 515 a, 515 b. The friction surfaces 514a, 514 b can be provided on the friction linings which are preferablyaffixed to the lamella 523 d and, in order to establish a connection,are provided with a channel 530, e.g., a pattern or array of grooves.The lamella 523 d is non-rotatably but axially movably mounted on thehub 506 a radially outwardly of the piston 516, and preferably coaxiallywith the latter, by way of a torsional vibration damper 523 analogous tothe damper 223 shown in and already described with reference to FIG. 3.

When the bypass clutch 513 is at least partially engaged, the piston 516cooperates with the friction surfaces 514 a, 514 b, 515 a, 515 b toestablish a fluid flow limiting or regulating arrangement 522 whichdetermines the rate of fluid flow between the plenum chambers 517 and518. In order to engage the bypass clutch 513, the compartment 518 areceives hydraulic fluid at a pressure higher than that in the chamber518; on the other hand, the pressure of fluid in the compartment 518 ais reduced below that in the chamber 518 if the clutch 513 is to bedisengaged. The compartment 518 a receives fluid from a source (notshown) by way of a bore or channel 504 p provided in a pipe 504 e of thestator. The channel 504 p communicates with a radial bore 504 n which,in turn, communicates with bores 507 e, 507 f respectively provided inthe transmission input shaft 507 and the additional shaft 507 c. Thelatter has an axial passage or bore or channel 507 d which communicateswith one or more radial bores 504 l discharging into the compartment 518a.

In the embodiment of FIG. 7, the admission of pressurized fluid into thecompartment 518 a is preferably independent of the fluid flow through.the fluid flow regulating arrangement 522, i.e., the flow of fluidthrough the plenum chambers 517, 518 can take place independently of thepressure of fluid in the compartment 518 a. The direction of fluid flowin and the sequence in which the chambers 517, 518 receive fluid dependsupon the intended use and/or mode of operation of the torque converter501 shown in FIG. 7.

In the embodiment which is shown in FIG. 7, the plenum chamber 517 isfirst to receive pressurized fluid; the admission of fluid into thechamber 517 takes place by way of a second conduit 504 p′ in the stator,an axial bore 504 o in the non-rotatable stator pipe 504 e, and at leastone axially parallel bore 504 q in the hub 506 a. The fluid which leavesthe chamber 517 enters the chamber 518 by way of the array of grooves530 at the fluid flow regulating arrangement 522. The fluid which leavesthe chamber 518 enters an evacuating conduit (not shown) provided in thestator pipe 504 by way of the chamber 517, grooves 530, compartment 518a and an opening 504 r.

The stator pipe 504 e and the transmission input shaft 507 arerespectively provided with openings 504 m, 507 d which supply hydraulicfluid to the transmission, e.g., to the torque sensor of a continuouslyvariable transmission (CVT), by way of at least one of additionalconduits 504 p, 504 p′, 519 a between the shaft 507 c and the inputshaft 507. It will be appreciated that certain bores, openings, channelsand like fluid path establishing passages which are referred tohereinabove and at least some of which are shown in FIG. 7 must betemporarily, intermittently or permanently sealed from each other inorder to establish paths for the flow of fluid to and from selectedchambers and/or compartments during different stages of operation of thetorque converter 501. The aforementioned CVT can be of the typedisclosed in any one of a number of US and foreign patents owned by theassignee of the present application, for example, in U.S. Pat. No.5,711,730 granted Jan. 27, 1998 to Friedmann et al. for “TORQUEMONITORING APPARATUS” and in the US patents referred to in this patentto Friedmann et al.

It is further clear that the additional or auxiliary piston 516 e andthe compartment 518 a can be utilized with advantage in numerous torqueconverters other than those specifically described and shown in thepresent case, i.e., in torque converters not employing a fluid flowregulating arrangement 522 (or an equivalent thereof) and/or anauxiliary drive. The required arrangements of conduits, channels, bores,holes and/or analogous paths for the flow of fluid will be selected independency upon the specific requirements of the modified torqueconverters. Furthermore, the flow of fluid from the various embodimentsof the improved torque converter can be limited and/or otherwiseregulated by specially designed and/or mounted valves. For example, afluid flow regulating arrangement (such as the one shown at 522 in FIG.7) can employ a valve which regulates the flow of pressurized fluid independency upon the temperature of such fluid, e.g., in such a way that,when the temperature of fluid rises while and/or because the bypassclutch operates with slip, the rate of fluid flow is increased. To thisend, the valve need not or should not be disposed in immediate or closeproximity to the regulator 522; for example, it often suffices toinstall a thermometer next to the regulator 522 and to utilize thethermometer as a means for transmitting signals to a fluid flowregulating valve which can be installed at a location close to or remotefrom the bypass clutch and from the fluid flow regulator.

FIG. 8 illustrates certain details of a torque converter 601 whichconstitutes a modification of the torque converter 101 shown in FIG. 2.The piston 616 of the bypass clutch 613 in the torque converter 601differs from the piston 116 in order to establish a modified fluid flowregulating arrangement 622. Furthermore, the torque converter 622employs modified friction generating members 614, 615 respectivelyhaving friction surfaces 614′, 615′. Such constituents of thearrangement 622 will be described in full detail with reference to FIGS.16 a and 16 b. The piston 616 has a circumferentially distributedannulus of resilient pressure transmitting components 629; these partswill be fully described and their function explained with reference toFIGS. 14 and 15.

FIGS. 9 to 13 a illustrate four presently preferred embodiments x(9),x(10), x(11) and x(12) of the improved fluid flow regulatingarrangement, and more specifically four embodiments of the arrangement122 shown in FIG. 2. In FIG. 9, the piston 116 of the bypass clutch 113cooperates with the radial wall 104 of the torque converter housing toregulate the flow of hydraulic fluid between the plenum cambers 117, 118(refer to FIG. 2) when the bypass clutch 113 is engaged. The wall 104has a cooling surface 104 k which confronts the piston 116 and isprovided with radially extending grooves or channels 130; such groovescan be impressed into the surface 104 k of the wall 104. Thenon-depressed portions of the cooling surface 104 k (i.e., the radiallyextending surfaces alternating with the grooves 130 constitute onefriction surface 114′ of the arrangement 122, and an annular frictionlining 115 on the radially outermost portion of the piston 116 defines asecond friction surface 115′ which bears upon the friction surface 114′when the clutch 113 is at least partly engaged. At such time, hydraulicfluid can flow only through the grooves 130 when the pressure of suchfluid in the chamber 117 exceeds that of fluid in the chamber 118.

The quantity of fluid flowing from the chamber 117 into the chamber 118depends upon the pressure differential between the fluid bodies in thesechambers as well as upon the combined cross-sectional area ofunobstructed portions of the grooves 130. In other words, such rate offluid flow is dependent upon several parameters including the pressuredifferential between the fluid bodies filling the chambers 117, 118, thetotal number of grooves 130, the extent to which the flow of fluidthrough these grooves is permitted by the friction surfaces 114′, 115′,and the depths, widths and lengths of the grooves (these grooves areassumed to have but need not have identical dimensions).

Another factor which influences or determines the rate of fluid flowthrough the grooves 130 is the temperature (and hence the viscosity) offluid leaving that one of the chambers 117, 118 wherein the fluidpressure is higher. The temperature of fluid rises as a result offriction moment developing at the surfaces 114′, 115′, i.e., thetemperature of fluid being forced through the grooves 130 increaseswhile the wall 104 and the piston 116 slip relative to each otherbecause, at such time, the fluid exchanges heat with the surfacessurrounding the grooves, Such heating of the fluid entails a drop ofviscosity, and the rate of flow of such fluid through the grooves 130increases if the pressure in the chambers 117, 118 remain unchanged.

It will be seen that, by properly selecting the parameters of thegrooves 130, one can achieve an optimal cooling of the surfaces 114′,115′ as well as an optimum rate of fluid flow between the chambers 117and 118. It will also be seen that, in the embodiment which is shown inFIG. 9, the fluid flow regulating arrangement operates in dependencyupon the extent of slip between the surfaces 114′ and 115′. If necessaryor desired, the parameters of the grooves 130 can be selected in such away that one can achieve a desired cooling effect with a very highdegree of accuracy. In other words, one can ensure that the operation ofthe bypass clutch 113 is at least substantially independent of changesof viscosity of the fluid.

In accordance with a presently preferred embodiment, the length l of thegrooves 130 (as measured radially of the wall 104, i.e., at right anglesto the plane of FIG. 13 a and as shown in FIG. 13), is between 10 and 50mm, most preferably between 10 and 30 mm. As shown in FIG. 9, the lengthof the grooves 130 can exceed the width of the friction lining 115; thisis desirable and advantageous because such dimensioning of the lengths lof the grooves 130 and of the radial width of the friction lining 115ensures a practically unimpeded inflow of fluid into and a practicallyunimpeded outflow of fluid from the grooves 130.

As concerns the hydrodynamic aspects, the important parameters includethe length l (FIG. 13), the width b (FIG. 13 a) and the depth t (FIG. 13a) of the grooves 130, especially the ratio of t to b. The edges 130′(see FIG. 13) of the surfaces bounding the grooves 130 may but need notbe rounded. The width b of a groove 130 can be within the range ofbetween about 0.2 and 20 mm, and the depth t can be less than 0.3 mm,preferably less than 0.15 mm. Still further, a groove 130 need not havean exactly rectangular cross-sectional outline; for example, thecross-sectional outlines of those end portions of the grooves 130 whichare adjacent their radially outermost portions (at 130 a in FIG. 13) canhave a trapeziform cross-sectional outline with each groove becomingwider as seen in a direction from the bottom toward the surface 114′ ofthe wall 104. The cross-sectional area of each groove 130 can increaseradially outwardly toward the radially outermost portion 130 a shown inFIG. 13.

Still further, each of the grooves 130 need not extend exactly radiallyof the wall 104; for example, at least some of these grooves can includeportions extending exactly or substantially circumferentially of thewall 104. It is also possible to replace equidistant grooves 130 withgrooves disposed at different distances from each other, as seen in thecircumferential direction of the wall 104.

An advantage of grooves 130 which include portions extending radiallyand portions extending circumferentially of the wall 104 is that therate of fluid flow through such grooves increases with increasing RPM ofthe wall 104.

The number of grooves 130 can vary within a wide range, e.g., between 8and 400. It is presently preferred to provide the wall 104 with asubstantial number of grooves, particularly between 100 and 300.

The making of grooves 130 in the surface 114′ of the wall 104 caninvolve a pressing, erosion, milling or any other suitable materialremoving or material displacing technique. The groove 130 shown in FIG.9 is assumed to have been impressed into the surface 114′ of the wall104.

FIG. 10 illustrates a portion of a modified fluid flow regulatingarrangement x(10) wherein the grooves 130 b are obtained by providingthe wall 104 with radially extending rib-shaped projections 130 c atthat side which faces away from the piston 116 of the bypass clutch.Thus, the grooves 130 b of FIG. 10 are obtained by displacing portionsof the material of the wall 104 away from the piston 116, i.e., into thesurface 114′.

FIG. 11 shows a portion of a fluid flow regulating arrangement x(11)which is the opposite of that shown in FIG. 10. Thus, the left-hand sideof the wall 104 is provided wth elongated grooves or recesses 130 dwhich are obtained by depressing the material of the wall 104 toward thepiston 116. Consequently, the grooves (not shown) at the surface 114 areflanked by ribs which project beyond the surface 114. In other words,the grooves in the wall 104 of FIG. 11 are obtained as a result ofraising elongated radially extending rib-shaped portions of the materialof the wall 104 toward the adjacent left-hand surface of the piston 116.

The making of the projections shown at the right-hand side of the wall104 depicted in FIG. 11 can involve the use of a suitable tool orimplement (not shown) having raised portions which impress the groovesor recesses 130 d to thus provide the surface 114′ with raised portionswhich, in turn, flank grooves having open sides facing the surface 115′of the friction lining 115 on the piston 116.

The fluid flow regulating arrangement x(12) of FIG. 12 does not employany grooves in the surface 114′ and/or 115′. Instead, that side of thewall 104 which confronts the piston 116 carries a continuous orcomposite annular layer 131 of a material which is permeable to thefluid filling the chambers 117, 118. The layer 131 can be made of or cancontain a sintered substance, a porous ceramic material (e.g., porousglass), a temperature-resistant porous organic plastic material or thelike. The surface 114′ of such layer 131 a cooperates with the surface115′ of the friction lining 115 on the adjacent surface of the piston116.

FIG. 12 shows the bypass clutch which employs the permeable layer 131 indisengaged condition, i.e., the layer 131 is out of contact or not insufficient contact with the surface 115′ of the friction lining 115 onthe piston 116. If the piston 116 is moved to the left so that thebypass clutch including the structure shown in FIG. 12 is engaged tooperate with or without slip, the hydraulic fluid is forced to penetratethrough the permeable layer 131 as soon as the pressure of fluid in oneof the chambers 117, 118 exceeds the fluid pressure in the otherchamber. Heat which develops as a result of frictional engagementbetween the exposed surface 114′ of the layer 131 and the surface 115′of the friction lining 115 (while the bypass clutch operates with slip)is withdrawn by the. flowing fluid. The rate of flow of fluid throughthe porous layer 131 depends upon the porosity of the material of suchlayer and the viscosity (temperature) of the fluid.

The layer 131 is secured to the wall 104 by rivets 131 a (one shown inFIG. 12). Alternatively, the layer 131 can be secured to the wall 104 bya suitable adhesive, by projections provided on the wall 104 andextending into complementary recesses in the left-hand side of the layer131, and/or in any other suitable manner. Furthermore, the layer 131 canbe formed by applying to the wall 104 one or more films of a materialwhich, when hardened or set, constitutes the layer 131.

It is clear that the porous layer 131 can be applied to the piston 116and that the wall 104 can carry a friction lining 115 or bears directlyupon the permeable layer on the piston 116. Still further, it ispossible to provide two porous layers 131, one on the wall 104 and theother on the piston 116. It is also possible to provide the exposed sideof the porous layer 131 with a friction lining which bears directly uponthe adjacent surface of the piston 116 or upon a friction lining on thepiston 116 when the bypass clutch embodying the structure of FIG. 12 oran analogous structure is at least partially engaged.

FIGS. 14 and 15 illustrate the distribution of and the manner ofmounting the resilient pressure transmitting members or components 629one of which is shown in the upper part of FIG. 8. For the sake ofsimplicity, such components will be referred to as bellows since eachthereof defines at least one internal space which can receive anddischarge a quantity of fluid. As can be seen in FIG. 14, the piston 616of the bypass clutch 613 carries an annular array of equidistant andrather closely adjacent oval bellows 629 each of which has its marginalportion affixed to the radially outermost portion of the piston 616 (asat 629 a). The connections 629 a can be established by an adhesive, bywelding or in any other suitable manner.

For example, the bellows 629 can be made of a metal (such as a thinlayer of sheet metal), of rubber or of any other suitable material whichcan perform the functions to be described hereinafter. The oval bellows629 can be replaced with circular or otherwise configurated components.

The central portion. of each bellows 629 registers with a discrete port629 a of piston 616; each such port permits hydraulic fluid to enterinto or to issue from the respective bellows. The ports 629 b togetherform a circular array. The bellows 629 change their volumes independency upon the pressure differentials between their interior andthe surrounding atmosphere. Such volumetric changes are possible due tothe deformability of the material of the bellows. The bellows 629 shownin FIGS. 8, 14 and 15 are assumed to consist of thin metallic sheetmaterial.

FIG. 16 a shows an empty (deflated) bellows 629 and shows that thisbellows is located at the side of the piston 616 facing away from thefluid flow regulator 622. FIG. 16 b shows an at least partially inflatedbellows 629. Each of FIGS. 16 a, 16 b shows the bypass clutch includingthe wall 604 and the piston 616 in disengaged condition in order tofacilitate the interpretation of the manner in which variousconstituents of the bypass clutch and of its fluid flow regulator 622are affixed to each other. However, it is to be borne in mind that theregulator 622 is activated and that the bellows 629 can perform theirintended functions only or primarily when the bypass clutch 613 is atleast partly engaged.

FIG. 16 a shows that the friction lining 614 at the right-hand side ofthe wall 604 has a friction surface 614′ provided with a recess 630 aportion of which registers with the port 629 b of the piston 616. Eachrecess 630 has an open radially inner end and a closed radially outerend. When the piston 616 turns relative to the wall 604 and/or viceversa, each port 629 b communicates with each of the recesses 630 onceduring each complete revolution of the parts 604, 615 relative to eachother.

It is now assumed that the pressure in the plenum chamber 618 shown inFIG. 16 a rises above that in the chamber 617 (reference should be hadagain to the description of the mode of operation of the torqueconverter 101 shown in FIG. 2). Therefore, the fluid in the chamber 18deforms the bellows 629 whenever the respective ports 629 b communicatewith the adjacent recesses 630 so that a certain amount of fluid canflow in the recesses 630 radially inwardly and into the chamber 617. Aninflated bellows 629 is shown in FIG. 16 b, and a deflated bellows isshown in FIG. 16 a. The flow of fluid from the bellows 629, through theports 629 b, through the recesses 630 and into the chamber 617 causes acooling of the surfaces 614′, 615′ which slide relative to each otherwhile the wall 604 and the piston 616 turn relative to each other whenthe bypass clutch operates with slip.

The bellows 629 are refilled, again and again, during successive stagesof angular movements of the parts 604, 616 relative to each other whenthe ports 629 b communicate with radially outwardly extending recesses630 a (see FIG. 16 b) which alternate with the recesses 630 and are alsoprovided in the friction surface 614′ of the friction lining 614 on thewall 604. Each recess 630 a has a closed radially inner end (disposedradially inwardly of the ports 629 b) and a radially outer endcommunicating with the chamber 618. Each bellows 629 receives fluid fromthe chamber 618 when the respective port 629 b communicates with one ofthe radially outwardly open recesses 630 a.

The just described repeated and at least partial emptying and at leastpartial refilling of the bellows 629 takes place as long as the wall 604and the piston 616 turn relative to each other, i.e., as long as thebypass clutch operates with slip. Such repeated refilling and emptyingof the bellows 629 is interrupted whenever the bypass clutch operateswithout slip and whenever the bypass clutch is disengaged (i.e., whenthe friction surfaces 614′, 615′ are out of frictional engagement witheach other).

It will be seen that the bellows 629 can be said to cooperate with or toform part of the fluid flow regulating arrangement 622. A feature commonto the regulating arrangement 622 and to the bellows 629 is that eachthereof operates in dependency upon the presence or absence and/orextent of slip of the surfaces 614′ 615′ relative to each other.

The number of ports 629 b and the numbers of recesses 630, 630 a can bereadily selected in such a way that the likelihood of vibrations and/ornoise generation, as a result of repeated (rhythmical) overlapping ofthe recesses 630, 630 a with the ports 629 b to bring about repeatedfilling and emptying of the bellows 629, is very remote or nil. This notonly applies to the parts 613, 616 but also to all component parts ofthe improved torque converter as well as to other component parts in thepower train and/or in other units of-a motor vehicle.

The number of ports 629 b is preferably different from that of therecesses 630, 630 a, and such numbers preferably have a large commondenominator.

FIGS. 17 a and 17 b show a modified assembly of parts in and at thefluid flow regulator of a bypass clutch 613 a. The bellows 629 (only oneshown) are mounted on the radially outermost portion of the piston 616,the same as the friction lining 615; this friction lining is notprovided with recesses 630, 630 a of the type shown in FIGS. 16 a and16b; instead, such recesses are provided in the friction surface 614′ ofthe wall 604 and the friction lining 615 is provided with ports 629′registering with the ports 629 b in the radially outermost portion ofthe piston 616. The grooves or recesses 630, 630 a are impressed ormilled or eroded into the right-hand side of the wall 604.

FIGS. 18 a and 18 b illustrate a portion of a bypass clutch 613 cwherein the bellows 629 are borne by the outer side of the wall 604 andthe piston 616 carries a friction lining 614 with recesses 630, 630 a ofthe type shown in FIGS. 16 a and 16 b. The recesses 630 a, 630 b areprovided in the surface 614′ of the friction lining 614, and the ports629 b are provided in the wall 604.

FIGS. 19 a and 19 b illustrate, drawn to a larger scale, certain detailsof a bypass. clutch 213 a constituting a modification of the bypassclutch 213 shown in FIG. 3. The leaf springs 216 a of the torqueconverter 213 are omitted, and the piston 216 of the bypass clutch 213 ais non-rotatably but axially movably affixed to the inner side of thetubular radially outermost portion of the torque converter housing 204 aby two sets of mating gear teeth 216 a′.

FIGS. 19 a and 19 b show the bypass clutch 213 a in disengaged conditionin order to facilitate the understanding of the relationships betweenvarious interconnected and relatively movable parts; however it will beappreciated that the illustrated parts cooperate only when the clutch213 a is at least partly engaged. The same applies for the frictionclutch 213 b which is shown in FIGS. 20 a and 20 b.

The friction lamella 223 d which is shown in FIGS. 19 a and 20 a carriesa first friction lining 214 a having a friction surface 214 a′confronting a friction surface 215 b′ at the inner side of the wall 204,and a second friction lining 214 b having an exposed friction surface214 b′ confronting a friction surface 215 a′ of the piston 216. A set ofinflatable receptacles (called bellows) 229 is provided at theright-hand side of the piston 216, and the latter has openings 229 b(hereinafter called ports) communicating with successive opening orports 229 c in the lamella 223 d.

The lamella 223 d further carries a second friction lining 214 b havingan exposed friction surface 214 b′ confronting a friction surface 215 b′on the piston 216. In FIG. 19 a, the illustrated bellows 229 can receivefluid from the chamber 217 via recesses 230 a provided in the frictionsurface 214 a′ of the friction lining 214 a, ports 229 c of the lamella223 d and ports 229 b in the piston 216.

In FIG. 19 b, the reference character 230 denotes one of those recesseswhich alternate with the recesses 230 a (one shown in FIG. 19 b) but areopen toward the chamber 217. Fluid can enter the bellows 229 viarecesses 230 a, ports 229 c and ports 229 b. In FIG. 19 a, fluid canenter the bellows 229 from the chamber 218 via form-locking connection216 a′ and/or through one or more openings (not shown in FIG. 19 a) inthe piston 216 between the connection 216 a′ and the friction surface215 b′ and thereupon through the ports 229 b.

The grooves 230 are provided in the surface 214′ of the friction lining214 a which engages the friction surface 215 a′ of the wall 204 in theengaged condition of the friction clutch 213 a. In order to establishcommunication between the ports 229 b, the friction linings 214 a, 214 band the lamella 223 d are provided with the ports 229 c.

The emptying of the bellows 229 is shown in FIG. 19 b. The recesses 230a (FIG. 19 a) alternate with the recesses 230 (FIG. 19 b). The exactmanner in which the fluid is caused or permitted to leave the bellows229 is the same as or analogous to that already described with referenceto FIG. 16 a.

FIGS. 20 a and 20 b respectively illustrate the emptying and refillingof bellows 229 in a manner analogous to that already. described withreference to FIGS. 19 a and 19 b., The difference between the bypassclutches 213 a and 213 b of FIGS. 19 a–19 b and 20 a–20 b is that, inthe clutch 213 a, recesses are provided in the friction surface 215 b′of the friction lining 215. Consequently, the ports 229 c of FIGS. 19a–19 b are not necessary in the friction clutch 213 b of FIGS. 20 a–20 bbecause the fluid flowing between the ports 229 b and the recesses 230or 230 a shown in FIGS. 20 a–20 b need not flow through part 223 d.

The features of the friction clutches 213 a, 213 b respectively shown inFIGS. 19 a–19 b and 20 a–20 b can be combined in a single torqueconverter, i.e., each of the friction linings 614 a, 614 b can beprovided with recesses 230, 230 a. In such embodiment of the presentinvention, alternating bellows 229 are or can be arranged torespectively receive and/or discharge fluid by way of channels 230, 230a provided in the friction linings 214 a and 214 b.

FIG. 21 illustrates a portion of a torque converter having a bypassclutch 213 d which constitutes a further modification of the clutch 213shown in FIG. 3. The friction lamella 223 d′ is flanked by two frictionlinings 214′, 214″ which are affixed to the wall 204 and to the piston216, respectively. The piston 216 is axially movably but non-rotatablyaffixed to the housing including the wall 204 by leaf springs 216 a. Thefriction linings 214′, 214″ frictionally engage the respective sides ofthe lamella 223 d′ when the bypass clutch 213 d is at least partiallyengaged.

The left-hand side of the lamella 223 d′ is provided with a profile 230b which varies in the circumferential direction and the details of whichare shown in FIG. 22. The left-hand (233 b) and right-hand (233 a) sidesof the lamella 223 d′ (as seen in FIG. 22) constitute friction surfaceswhich respectively engage the adjacent friction linings 214′ and 214″.The surfaces 233 b and 233 a are respectively provided with recesses 232a, 232 b; these recesses form part of the fluid flow regulatingarrangement 222, i.e., of the arrangement which regulates the flow offluid between the plenum chambers 217, 218 (see FIG. 3) when thestructure shown in FIGS. 21 and 22 is incorporated into-the torqueconverter 201 of FIG. 3. The arrangement 222 then serves to determinethe rate of fluid flow between the chambers 217, 218 in dependency uponthe temperature (and hence the viscosity) of the fluid. As concerns theparameters (such as the depth, the width, the length, the number and theorientation) of the grooves 232 a, 232 b, reference should be had to thedescriptions of the bypass clutches shown in FIGS. 16 a–16 b, 17 a–17 band 18 a–18 b, especially in FIGS. 17 a–17 b and by bearing in mind thatthe structure actually shown in FIGS. 21 :and 22 does not employ bellows(such as those shown at 629 in FIGS. 16 a–18 b).

FIGS. 23 and 24 illustrate a structure which constitutes a modificationof that shown in FIG. 12. In the bypass clutch 213 a of FIG. 23, afriction lamella 223 d″ carries two porous layers 231 a, 231 b which arerespectively adjacent a friction lining 214″ on the wall 204 and afriction lining 214′ on the piston 216. The friction lining 214′ can beaffixed to the porous layer 231 a instead of to the piston 216, and thefriction lining 214″ can be affixed to the porous layer 213 b (insteadof to the wall 204). Furthermore, the bypass clutch 213 a can utilizeall of the parts shown in FIG. 23 plus at least one additional frictionlining (affixed to the porous layer 231 a or 231 b).

In FIG. 24, the bypass clutch 213 b comprises a single porous layer 231(e.g., a layer made of sintered metal) which is riveted to the frictionlamella 223 d″. The layer 231 has friction surfaces 215, 215 a which(when the clutch 213 b is at least partly engaged) respectively bearupon friction linings 214′ (provided on the piston 216) and 214″(provided on the wall 204). The radially outermost portion of thefriction lamella 223 d″ is located radially inwardly of the frictionlinings 214′. 214″.

FIG. 25 shows certain details of a bypass clutch 613 d having a frictiongenerating device 621 composed of parts 614, 615. A piston 616 dreplaces the piston 116 or 616 of FIG. 2 or FIG. 8 to allow for anadvantageous further modification of the fluid flow regulatingarrangement 122 of FIG. 2 or 622 of FIG. 8. The fluid flow regulatorembodying certain parts of the structure shown in FIG. 25 serves toregulate the flow of hydraulic fluid between the plenum chambers 617 and618.

The wall 604 of FIG. 25 carries a friction lining 614′ which is providedwith circumferentially distributed recesses or grooves 630d extendingradially outwardly to register with ports 629 b in the radially outerportion of the piston 616 d. The radially outer ends of the recesses 630d are closed from the chamber 618 (when the bypass clutch 613 d of FIG.25 is at least partly engaged) but the radially inner ends of suchrecesses are open toward the chamber 617.

The bellows 629 are not used in the bypass clutch 613d; instead, theports 629 b of the piston 616 d communicate directly with the chamber618. When the piston 616 d and the housing (including the wall 604) arecaused to turn relative to each other, the ports 629 b move into andbeyond positions of register with the recesses 630 d of the frictionlining 614′ on the wall 604 to thus respectively establish paths for theflow of fluid between the chambers 617 and 618. Such repeated flow offluid between the chambers 617, 618 ensures that at least the frictionlining 614′ is adequately cooled as soon and as long as the bypassclutch 613 d operates with slip.

If the pressure of fluid in the chamber 618 rises above that in thechamber 617, i.e., if the piston 616 d is moved axially toward the wall604, the extent of relative angular movement of the piston 616 d and thehousing (including the wall 604) of the torque converter decreases andcomes to a halt when the clutch 616 d is fully engaged. The number ofports 629 b and/or the number of recesses 630 d can be selected in sucha way that the likelihood of unsatisfactory or unacceptable overlap isremote or nil; this can be readily accomplished by proper selection ofthe numbers and/or proper distribution of the ports 629 b and recesses630 d.

Furthermore, and as actually shown in FIG. 25, one can provide a closingdevice or lid 635 which, when the bypass clutch 613 d is engaged, sealsthe ports 629 b from the plenum chamber 618 so that there can be no flowof fluid from the chamber 618, via ports 629 b and recesses 630 d, andinto the chamber 617 (wherein the fluid pressure is assumed to be lowerthan in the chamber 618 when the bypass clutch 613 d is fully engaged,i.e., when such bypass clutch operates without slip). The reason for theprovision of the closing device 635 is that there is no need to cool thefriction lining 614′ when the bypass clutch 613 d is fully engaged sothat the wall 604 and the piston 616 d cannot slip relative to eachother.

It is clear that the closing device 635 can be designed to close andactually seal only some of the ports 629 b from the plenum chamber 618.

FIG. 26 shows, drawn to a larger scale, the structure within thephantom-line circle Y in FIG. 25. FIG. 27 is a view as seen in thedirection of arrow X in FIG. 26, and FIG. 28 is a view as seen in thedirection of arrow W in FIG. 25. The closing device 635 comprises aseries of tongues or flaps 635 a which are pivotable to movesubstantially axially of the bypass clutch 613 d. The tongues 635 a formintegral parts of or are pivotably mounted on a ring-shaped carrier 635which is welded, riveted or adhesively or otherwise affixed to thepiston 616 d. It is preferred to make the carrier 635 b of a resilientmaterial and to ensure that the tongues 635 a tend to assume theirinoperative or idle positions (shown in FIGS. 25 to 27) in which theypermit fluid to flow from the chamber 618 into the ports 629 b. Forexample, the carrier 635 b and its tongues 635 a can be made of thinlayers of spring steel. The thickness and/or the resiliency of thematerial of the carrier 635 b are selected in such a way that thetongues 635 a are compelled to yield and to pivot to their operative orclosed positions (to seal the respective ports 629 b from the chamber618) as soon as the pressure of fluid in the chamber 618 ries to a valueindicating that the clutch 613 d of FIGS. 25–28 is engaged, i.e., thatthe wall 604 and the piston 616 d do not turn relative to each other.When the pressure differential between the bodies of fluid in thechambers 617, 618 decreases, the innate resiliency of the tongues 635 asuffices to initiate a movement of the tongues to the open positionsshown in FIGS. 25 to 27.

In order to even more reliably ensure pivotal movements of the tongues635 a to their open or inoperative positions as soon as the piston 616 dand the wall 604 are free to turn relative to each other, the frictionlining 614′ of FIG. 25 is provided with at least one groove which isopen radially outwardly; such groove or grooves permits or permit entryof fluid which exerts pressure upon the tongues 635 a and ensures orensure that the tongues reassume the open positions of FIGS. 25–27 assoon as the wall 604 and the piston 616 begin to turn relative to eachother. Otherwise stated, the just mentioned groove or grooves in thefriction lining 614′ ensures or ensure that the pressure of fluid at theinner sides of the tongues 635 a is the same as at their outer sides(i.e., in the plenum chamber 618) as soon as the wall 604 and the piston616 d begin to turn relative to each other so that the innate tendencyof the tongues 635 a suffices to maintain them in open positions whenthe clutch 613 d is partially engaged so that it operates with slip.

By embodying the structure of FIGS. 25–28 in the bypass clutch of FIG. 2and/or 8, one ensures that the respective fluid flow regulating assembly(122 or 622) even more reliably ensures adequate cooling of thehydraulic fluid by exchange of heat as long as the respective bypassclutch operates with slip, and that the extent of cooling iscommensurate with (a) the speed of relative angular movement between thetorque converter housing (wall 104 or 604) and the piston (116 or 616),and (b) the extent of pressure differential between the bodies of fluidin the plenum chambers (117 and 118 or 617 and 618). On the other hand,the tongues 635 a in the structure of FIGS. 25–28 also ensure that thecirculation of fluid through the fluid flow regulating arrangement 122or 622 is interrupted when a cooling of fluid is not necessary, i.e.,when the bypass clutch embodying the structure of FIGS. 25–28 isdisengaged or fully engaged.

The structure which is shown in FIGS. 25–28 (or one or more structuraland functional equivalents thereof) can be utilized with equal orsimilar advantage in torque converters which are different from thoseshown in FIGS. 2 and 8, i.e., with differently configurated, mounted andassembled friction linings, friction lamellae and/or other constituentsof the fluid flow regulating arrangements. By way of example only, thestructure shown in FIGS. 25–28 can be incorporated into torqueconverters embodying the features of the structures shown in FIGS. 16 ato 20 b.

FIGS. 29 a to 29 k respectively illustrate portions of friction linings636 a to 636 k which can be utilized in lieu of previously describedfriction linings (such as those shown in FIGS. 16 a to 20 b) to ensureeven more predictable flow of fluid between the two plenum chambers (notshown in FIGS. 29 a to 29 k).

For example, if one utilizes a fluid flow regulating arrangement 622(FIG. 8) or 622 a (FIG. 25), it is advisable to employ radially inwardlyopening grooves or recesses 636 a″–636 k″ (see FIGS. 29 a–29 k) as wellas radially outwardly open recesses 636 a′–636 k′ in such numbers thatthe overall number of radially outwardly opening recesses (e.g., 636 a′)matches or approximates the overall nmber of radially inwardly openingrecesses (e.g., 636 a″). Moreover, individual radially inwardly openingrecesses (such as 636 a″) or groups of such recesses can alternate withindividual radially outwardly opening recesses (such as 636 a′) orgroups of such recesses, as seen in the circumferential direction of therespective friction ring (such as 636 a). The recesses or grooves ofeach set can be equidistant from each other and can be straight,arcuate, undulate, zig-zag shaped, comb-shaped, T-shaped, V-shapedand/or otherwise configurated.

It is also possible to alternate groups of two or more inwardly openingrecesses (such as 636 a″) with individual outwardly opening recesses(such as 636 a′); such arrangement can be resorted to in the embodimentof FIG. 25).

FIG. 29 a shows that the radially inner ends of the recesses 636 a′, 636a″ extend circumferentially of the friction lining 636 a. If sucharrangement is used in the embodiment of FIGS. 16–16 b, it ensureslonger-lasting communication of successive alternating recesses 636 a′and 636 a″ with successive ports 629 b shown in FIGS. 16 a and 16 b.

The recesses or grooves 636 b and 636 c of FIGS. 29 b and 29 c extendradially of the respective friction linings 636 b, 636 c; therefore, theintervals of communication with the ports 629 b of FIGS. 16 a–16 b (ifthe friction lining shown in FIGS. 16 a and 16 b is replaced with thefriction lining 636 b or 636 c) are relatively short if and when thewall 604 and the piston 616 of FIGS. 16 a and 16 b are caused to turnrelative to each other. The depths of the recesses 636 b′, 636 b″ aresuch that their closed inner ends communicate with successive ports 629b if the friction lining 636 b replaces the friction lining shown inFIGS. 16 a and 16 b.

The recesses 636 c′, 636 c″ of the friction lining 636 c shown in FIG.29 c are much longer than those shown in FIG. 29 b.

The inclination of the straight recesses 636 d′, 636 d″ in the frictionlining 636 of FIG. 29 d is dependent upon the desired duration ofcommunication with successive ports 629 b if the friction lining 636 dreplaces the one shown in FIGS. 16 a and 16 b. The illustrated recesses636 d′, 636 d″ are inclined in the same direction, i.e., clockwise, asseen in FIG. 29 d; however, they can be inclined in opposite directionsif so required or desirable or advantageous for a specific mode of fluidflow regulation.

Each of the recesses 636 e′, 636 e″ (in the friction lining 636 e ofFIG. 29 e), 636 f′, 636 f″ (in the friction lining 636 f of FIG. 29 f)and 636 g′, 636 g″ (in the friction lining 636 g of FIG. 29 g) has twoopen ends which extend inwardly from the outer and inner edge faces ofthe respective friction lining. The recesses of the friction liningsshown in FIGS. 29 e to 29 g can have identical (FIGS. 29 e, 29 g) ordifferent (FIG. 29 f) shapes and/or sizes, such as part circular,U-shaped, trapeziform or U-shaped outlines.

FIGS. 29 h and 29 i respectively show recesses 636 h′, 636 h″ and 636i′, 636 i″ having widths (as seen circumferentially of the respectivefriction rings 636 h, 636 i) greatly exceeding their depths.Furthermore, the depths of the recesses 636 i′, 636 i″ varycontinuously, as seen in the circumferential direction of the frictionring 636 i.

It is to be noted that the FIGS. 29 a–29 k illustrate merely arelatively small number of different recesses 636 a′–636 k′ and 636a″–636 k″. Thus, it is possible to combine the shapes actually shown inthese Figures to arrive at a host of additional configurations havingconstant or varying depths and/or widths and/or lengths, depending uponthe desired nature, duration and other characteristics of fluid flowbetween the two plenum chambers.

FIG. 29 j shows a friction lining 636 j wherein the zig-zag shapedrecesses 636 j′, 636 j″ are dimensioned, configurated and oriented toensure extensive (pronounced) cooling of the friction lining becausesuch recesses can come into frequent and long-lasting contact withsuccessive ports 629 b (if the friction lining 636 j is utilized in thestructure shown in FIGS. 16 a and 16 b).

The comb-shaped grooves 636 k′, 636 k″ in the friction lining 636 k ofFIG. 29 k also ensure long-lasting communication of their ridges withsuccessive ports 629 b if the friction lining 636 k is utilized in lieuof the friction lining shown in FIGS. 16 a and 16 b.

At least some of the grooves or recesses shown in FIGS. 29 a–29 k can beutilized in parts other than friction linings, e.g., in lieu of therecesses 630 a, 630 respectively shown in FIGS. 17 a and 17 b; therecesses 630 a, 630 are provided in the inner side of the wall 604,i.e., in a portion of the housing of the torque converter including thestructure shown in FIGS. 17 a and 17 b.

Still further, it is possible to provide recesses or grooves of the typeshown in FIGS. 29 a to 29 k in the piston of the bypass clutch or in afriction lamells (see the part 223 d′ shown in FIGS. 21 and 22).

FIG. 30 shows a hydrokinetic torque converter 701 having a fluid flowregulating arrangement 722 which is effective to influence the operationof the bypass clutch 713, namely to regulate the rate of fluid flowbetween the wall 704 of the housing 704 a of the torque converter andthe axially movable piston 716. The controlling factor is the differencebetween the RPM of the wall 704 and that of the piston 716.

The reference character 737 denotes a metering pump which is installedin the hub 706 a of the turbine 706 in the housing 704 a. The piston 716and the turbine constitute the output members of the bypass clutch 713.A torsional vibration damper 723 is employed to prevent the transmissionof vibrations from the piston 716 and/or from the turbine 706 to the hub706 a and hence to the transmission when the bypass clutch 713 isengaged to operate with or without slip.

The pump 737 is rotatable relative to and is confined in the hub 706 a.A safety ring 737 a is provided to prevent axial movements of the pump737 relative to the hub 706 a. The housing 737 b of the pump 737 isnon-rotatably connected with the wall 704 but is rotatable relative tothe hub 706 a. The non-rotatable connection between the pump housing 737b and the wall 704 comprises at least one projection or stud 737 cprovided on the pump housing and extending into a socket 704 f′ of aplug or stud 704 f which is welded to the wall 704. The pump housing 737b confines a pumping element 738 here shown as a sphere which is movableback and forth in a preferably cylindrical internal chamber or space 741to seal the opening or outlet 739 or 740 of the pump 737. The openings739, 740 are or can be surrounded by suitable sealing elements (such aselastic washers, O-rings or the like). The openings 739, 740respectively confront conduits 742, 743 which are provided in the hub706 a and respectively communicate with an inlet 719 a and an outlet 719b for hydraulic fluid.

When the housing 704 a and the plug 704 f turn relative to the hub 706 aand/or vice versa, the openings 739, 740 alternately but simultaneouslycommunicate with the conduits 742, 743 in response to successive 180°turns of the pump housing 737 b. Thus, when the wall 704 turns relativeto the hub 706 a and the pressure of fluid in the conduit 743 exceedsthat in the conduit 742, successive quantities of fluid entering chamber741 are transferred from the conduit 743 into the conduit 742. Thespherical pumping element 738 is caused to move in the chamber 741 backand forth first into sealing position relative to the opening 739,thereupon (as a result of rotation of the pump housing 737 b through180° with the wall 704 relative to the hub 706 a) to the position inwhich it seals the opening 740, again into a position in which it sealsthe opening 739, and so forth. This causes the transfer of meteredquantities of fluid from the conduit 743 into the conduit 742. Suchpumping of successive metered quantities of fluid continues as long asthe wall 704 and the hub 706 a turn relative to each other (this alsoinvolves rotation of one of these parts relative to the other part).

When the clutch 713 is disengaged, the pressure in the conduit 742matches that in the conduit 743 so that the rate of fluid flow betweenthese conduits is practically nil even if the wall 704 turns relative tothe hub 706 a and/or vice versa (due to slip of the turbine 706 and thepump 705 relative to each other).

The means for conveying metered quantities of fluid from the conduit 742into the region of the bypass clutch 713, namely to the locus of director indirect frictional engagement of the piston 716 with the wall 704,i.e., for removing heat from the friction surfaces 714′, 715′, includesa disc-shaped member 744 which cooperates with the piston 716 to definea chamber 745 which communicates with the conduit 742 and is sealed fromthe plenum chamber 718. The member 744 can constitute an injectionmolded plastic part or an embossed sheet metal part; this member issealed outwardly against the piston 716 and inwardly against the hub 706a.

The reference character 723 g denotes a rivet constituting one of thefasteners which secure the the torsional vibration damper 723 to thepiston 716; the member 744 can have a cutout for each of the fasteners723 g, and each such cutout is surrounded by a seal (not shown) whichensures that fluid entering the chamber 745 is compelled to flow fromthe openings 739, 740 to the bypass clutch 713.

The radially outermost portion of the piston 716 has an annulus of ports729 b which direct pressurized fluid from the chamber 745 against thefriction lining 714′, and such fluid ultimately enters the plenumchamber 717 or 718 to exchange heat with the friction lining 714′ and totransfer such heat to the body of fluid in the chamber 717 or 718. Thereference character 715 denotes a friction surface provided on thefriction lining 714′ and having grooves of the type shown, for example,in FIG. 19 b to direct the fluid into the plenum chamber 717. Thechamber 717 communicates with the outlet 719 b.

The aforementioned grooves (e.g., in the surface 715) can be of the typeshown in FIGS. 29 a to 29 k, except that all such grooves are laid outto convey hydraulic fluid from the ports 729 b (i.e., from the chamber745) into the chamber 717 (reference should be had to the grooves 636 a″to 636 k″ shown in FIGS. 29 a to 29 k.

The plenum chamber 718 of the torque converter 701 receives fluid fromthe inlet 719 a for pressurized fluid in a manner not specifically shownin FIG. 30; the path for the flow of fluid from the inlet 719 a of thetorque converer 701 to the chamber 718 is defined by parts not visiblein the sectional view of FIG. 30.

FIGS. 31, 32 a and 32 b illustrate the details of a further fluid flowregulating arrangement 822 which constitutes a modification of thearrangement shown in FIG. 30. The piston 816 of the bypass clutch in thetorque converter which embodies the structure of FIGS. 31, 32 a and 32 bis provided with an annular array of circumferentially spaced-apartmetering pumps 837 (two shown in FIG. 31) which, in contrast to thecentrally mounted pump 737 of the torque converter 701 shown in FIG. 30,are mounted in the region of frictional engagement between the parts ofthe fluid flow regulating arrangement 822 when the clutch including thepiston 816 is at least partly engaged, i.e., when the wall 804 of thehousing of the torque converter and the piston 816 turn relative to eachother.

The character 814′ denotes a friction lining which can be affixed (e.g.,bonded) to the piston 816 or to the wall 804 (preferably to the wall).The pumps 837 are adjacent the radially outermost portion of the piston816; an advantage of such mounting of the pumps is that the delivery offluid to their inlets or intakes and the flow of fluid from theiroutlets are simpler and hence the entire torque converter is lessexpensive than that embodying the structure shown in FIG. 30.

The ends of the elongated pumps 837 are provided with outlets 839, 840constituted by pipes 839 a, 840 a (see FIG. 32 a) which are recessed inthe piston 816 to the extent determined by the stops 839 c, 840 c,respectively. The pipes 839 a, 840 a and a length of a pipe 837 cbetween them together constitute the housing 837 b of the respectivepump 837. The pumping element 838 is a sphere which is movable back andforth in the pipe 837 a all the way between the pipes 839 a, 840 a.

The pipes 839 a, 840 a can constitute composite (such as two-part)components made, e.g., in an injection molding machine, of a suitableplastic material. The same applies for several or all other parts ofeach pump 837.

The friction lining 814′ of the torque converter shown in part in FIGS.32 a and 32 b is assumed to be affixed to the wall 804 of the housing ofthe torque converter. This friction lining has radially outwardlyextending recesses or cutouts 830 which alternate with radially inwardlyextending recesses or cutouts 830 a. These recesses extend inwardly toan extent such that they communicate with the openings 839, 840 (theseare used as inlets or outlets) of successive pumps 837 when the wall 804and the piston 816 turn relative to each other. The spacing of therecesses 830, 830 a in the circumferential direction of the frictionlining 814′ is such that one thereof registers with the opening 839 of apump 817 while the other thereof registers with the opening 840. Theillustrated recesses 830, 830 a constitute but one of numerousembodiments which can be provided in the friction lining 814′; referencemay be had, for example, to FIGS. 29 a to 29 k.

If a friction lining (replacing the friction lining 814′ on the wall804) is replaced with a friction lining on the piston 816, the recesses830, 830 a or their equivalents are machined into or otherwise providedin that surface of the wall 804 which confronts the piston 816.

The mode of operation of the bypass clutch embodying the structure shownin FIGS. 31, 32 a and 32 b is such that, when the fluid flows from oneof the two plenum chambers (e.g., from the plenum chamber 118 shown inFIG. 2), such fluid is caused to enter the recesses 830 a in thedirection of arrows shown in FIG. 32 a to cause the spherical pumpingelement 838 to roll or to otherwise move in the pump chamber toward theopening 840 and to expel a metered quantity of fluid into the chamber817. Such movement of the pumping element 838 results in entry of astream of hydraulic fluid from the chamber 818 into the portion 841 ofthe pump chamber via opening 839 and in simultaneous expulsion (by thepumping element 838) of a stream of fluid from the portion 841 a of thepump chamber, via opening 840 and into the plenum chamber 117. The rateof fluid flow from the chamber 118 into the the chamber 117 is dependentupon the extent of angular movement of the piston 816 and the wall 804relative to each other. When the pumping element 838 reaches theright-hand end of the pump chamber (841+841 a), it seals the opening 840from the pump chamber and the latter is filled with fluid via opening839.

As the angular displacement of the parts 804, 816 relative to each othercontinues, the openings 839, 840 respectively communicate with therecesses 830, 830 a (see FIG. 32 b). The recess 830 a admits pressurizedfluid which causes the pumping element 838 to expel the contents of thepump housing 837 b via opening 839 and recess 830 into the chamber 817.At the same time, the chamber 841+841 a is filled with fluid enteringvia opening 840. This stage of operation of the pump 837 shown in FIGS.32 a and 32 b is completed when the pumping element 838 seals theopening 839. The above described alternating stages of operation arerepeated, again and again, as long as the bypass clutch including thepiston 816 and the wall 804 operates with slip. When the bypass cutch isfully engaged, a cooling of the friction lining 814′ and/or of theneighboring parts of the torque converter is no longer necessary; atsuch time, the pumping element 838 of each pump 837 at leastsubstantially seals one of the openings 839, 840 in the respective pumpto thus interrupt the flow of fluid between the plenum chambers 117 and118.

FIG. 33 illustrates a portion of a torque converter 901 having a bypassclutch 913 and constituting a further modification of the torqueconverter 101 shown in FIG. 2. The parts 914′, 915′ correspond to theparts 114′, 115′ of the torque converter 101. The bypass clutch 913comprises a piston 916 the radially outermost portion of which carries aring-shaped resilient sealing element 950 having a lip 951 arranged tosealingly engage the inner side of the wall 904. The characteristics(such as the Shore hardness and/or the modulus of elasticity) of thematerial of the sealing element 950 in the region of the lip 951 can beinfluenced by one or more reinforcing inserts (such as a wire ring orthe like) in such a way that the lip 951 sealingly engages the wall 904only when the pressure of fluid in the plenum chamber 918 exceeds thepressure of fluid in the plenum chamber 917 to a predetermined extent.

The axial profile (at 952) of the right-hand side of the wall 904 isimpressed (such as by embossing or by extruding) or otherwise formed toimpart to such side an undulate outline which varies as seen in thecircumferential directon of the bypass clutch. This profile 952 isengaged by the lip 951 when the pressure of fluid in the chamber 918rises to a predetermined level.

FIG. 34 b illustrates the lip of the sealing element 950 in full sealingengagement with the profiled inner side of the wall 904. The arrowsindicate the directions of rotary movement of the parts 904 and 916 (thesealing element 950 rotates with the piston 916). If the piston 916 andthe wall 904 begin to turn relative to each other, the stiffness of thereinforced lip 951 and/or the undulate shape of the profiled side 952 ofthe wall 904 and/or the drop of pressure in the chamber 918 (as comparedwith that of the chamber 917) causes the lip 951 to move away from theprofile 952 and to establish pathways 953 for the flow of fluid betweenthe chambers 917 and 918, e.g., from the chamber 918 into the chamber917. This is shown in FIG. 34 a. The friction lining 914′ can beprovided with recesses, channels, cutouts or like configurations whichextend radially of such friction lining and permit the flow of fluidbetween the chambers 917, 918 at a desired optimum rate when the parts904, 916 are caused or permitted to turn relative to each other. Thestructure shown in FIGS. 33, 34 a and 34 b also permits for an accurateregulation of fluid flow between the chambers 917, 918 to ensureadequate cooling of surfaces which are heated while the parts 904, 916are caused or permitted to turn relative to each other.

FIG. 35 shows a portion of a torque converter 1001 which embodies or canembody a fluid flow regulating arrangement corresponding to that shownat 22 in the torque converter 101 of FIG. 2, and which further comprisesa cooling unit or cooling assembly 1060 serving to cool the surfaces1015, 1014 of the friction linings 1014′, 1015′ in the bypass clutch1013. The cooling unit 1060 is installed at that side (1061) of the wall1004 which faces away from the piston 1016. It is also possible toinstall the cooling unit 1060 or a second cooling unit at that side ofthe piston 1016 which faces away from the wall 1004.

The reference character 1062 denotes a cooling chamber which extendsradially inwardly beyond the friction surfaces 1014, 1015 and, in theembodiment of FIG. 35, is defined by the wall 1004 and a sheet metalshroud 1063 which is sealingly secured (such as welded) to the outerside 1061 of the wall 1004. The cooling chamber 1062 has a sealableopening 1064 for admission or evacuation of a coolant 1065 partlyfilling the chamber 1062 and having a density which varies in responseto heating by friction heat developing when the parts 1004, 1016 of hebypass clutch 1013 are caused or permitted to slip relative to eachother. Such change of phase causes the body of coolant 1065 to storeenergy and to be accelerated radially inwardly due to a reduction ofdensity and the lesser action of centrifugal force whenever the housingwall 1004 and the piston 1016 turn relative to each other. This enablesthe coolant 1065 to exchange heat with relatively cool (cooler) housingwall portions 1004h and shroud portions 1063 a. Such cooling of thecoolant 1065 entails a rise of density and an increased action ofcentrifugal force, i.e., the coolant flows radially outwardly andremoves heat from the surface 1061 of the wall 1004 which is heated dueto slippage relative to the piston 1016.

The coolant 1065 in the chamber 1062 can be water, ammonia, sulfurhexafluoride, one of Freon substitutes and others with a phase changebetween liquid and gaseous. It is also possible to employ solidsubstances, such as sodium, which can undergo a pronounced phase changebetween gaseous and solid in response to temperature changes.

In order to ensure the establishment of optimum relationship between thephase changes and the development of friction heat while the bypassclutch 1013 operates with slip, the chamber 1062 can be maintained atsubatmospheric or superatmospheric pressure.

The cooling unit 1060 can be utilized with particular advantage intorque converters which employ conical bypass clutches because thisrenders it possible to install the cooling chamber 1062 in the conicalregions at the friction surfaces of such bypass clutches. This canresult in a substantial reduction of the space requirements (especiallyas seen in the axial direction) of torque converters embodying coolingunits of the type shown in FIG. 35.

The features of the numerous embodiments shown in FIGS. 1 to 35 can beutilized interchangeably and/or cumulatively without departing from thespirit and scope of the invention. Furthermore, the novel fluid flowregulating arrangements, bypass clutches, cooling units, fluidcirculating pumps, friction linings and other constituents of theaforedescribed torque converters can be utilized, with equal or similaradvantage, in many other types of torque converters for use in the powertrains of motor vehicles or elsewhere.

Numerous modes of assembling and operating the improved torque converterand/or its bypass clutch and/or the regulating means therefor aredisclosed on pages 31 to 60 in the aforementioned commonly ownedcopending German patent application Ser. No. 100 20 907.6 filed Apr. 28,2000. It is emphasized, again, that the German priority application,including the pages 31 to 60 thereof, is incorporated herein byreference, i.e., that it forms part of the present application.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying curent knowledge.,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of the aboveoutlined contribution to the art of hydrokinetic torque converters and,therefore, such adaptations should and are intended to be comprehendedwithin the meaning and range of equivalence of the appended claims.

1. A hydrokinetic torque converter, comprising: a housing rotatable about a predetermined axis; a pump rotatable by said housing about said axis; a turbine rotatable in said housing about said axis by and relative to said pump; means for rotating said housing; an output element rotatable about said axis and arranged to receive torque from said turbine; a fluid-operated bypass clutch disposed in said housing and arranged to transmit variable torque between said housing and said output element, said clutch including a driving component rotatable with said housing and a driven component rotatable with said output element and movable axially of said housing into and from frictional engagement—with and without slip—with said driving component; means for moving said driven component, including first and second plenum chambers containing bodies of hydraulic fluid at variable pressure with the provision for fluid flow between said chambers through said clutch; and at least one active means for regulating the fluid flow between said chambers in dependency upon the magnitude of torque being transmitted by the clutch, wherein the at least one active means permits the hydraulic fluid to intermittently flow through grooves formed in a friction lining associated with one of the components so as to regulate fluid flow between said chambers.
 2. The torque converter of claim 1, wherein said regulating means includes means for automatically altering the rate of fluid flow between said plenum chambers in response to variations of the slip between said components.
 3. The torque converter of claim 1, wherein said regulating means includes at least one channel provided in at least one of said components and arranged to establish a path for the flow of fluid between said chambers when said clutch is operated with slip.
 4. The torque converter of claim 1, wherein said regulating means is operative to increase the rate of fluid flow between said chambers in response to increasing slip between said components.
 5. The torque converter of claim 1, wherein said regulating means includes means for regulating the rate of fluid flow between said plenum chambers in dependency upon changes of RPM between said means for rotating said housing and said output element.
 6. The torque converter of claim 1, further comprising means for varying the pressure of fluid in at least one of said plenum chambers independently of said regulating means.
 7. The torque converter of claim 6, wherein said varying means is operative to vary the pressure of fluid in said at least one chamber as a function of changes of the RPM of said rotating means.
 8. The torque converter of claim 1, wherein the viscosity of fluid in the fluid flow between said plenum chambers varies in response to the changes of the extent of slip between said components and the rate of fluid flow between said chambers is regulated in response to variations of said viscosity.
 9. The torque converter of claim 1, wherein the temperature of fluid in the flow between said chambers varies in response to changes of the extent of slip between said components and the rate of flow between said chambers is regulated in response variations of said temperature.
 10. The torque converter of claim 1, wherein said regulating means includes at least one channel provided in at least one of said components and arranged to establish a path for the flow of fluid between said chambers when said clutch is operated with slip, and an adjustable barrier against the flow of fluid in said at least one channel.
 11. The torque converter of claim 1, wherein said driven component comprises a piston and at least one of said components comprises at least one friction lining contacting the other of said components in the engaged condition of said clutch.
 12. The torque converter of claim 1, wherein said clutch further comprises a lamella disposed between said components and movable axially of said housing, in response to axial movement of said driven component, into frictional engagement with said components in the engaged condition of said clutch.
 13. The torque converter of claim 1, wherein said clutch further comprises at least one friction lining borne by one of said components and frictionally engaging the other of said components in the engaged condition of said clutch, said components and said friction linings having friction surfaces each of which engages another of said surfaces at least in the engaged condition of said clutch, said regulating means having recesses extending at least substantially radially of said axis and provided in at least one of said surfaces to establish at least a portion of said fluid flow in the engaged condition of said clutch.
 14. The torque converter of claim 1, wherein the at least one active means includes at least one expandable bellows that is formed as part of a piston associated with the by-pass clutch as defines at least one internal space which can receive and discharge a quantity of fluid.
 15. The torque converter of claim 14, wherein the bellows has its marginal portion affixed to a radially outermost portion of the piston and is provided on a face opposite a face that carries the friction liner.
 16. The torque converter of claim 14, wherein the piston contains at least one port that is in fluid communication with the at least one internal space to permit the fluid to enter and flow from the internal space.
 17. The torque converter of claim 16, wherein the driving component has a friction surface provided with a recess a portion of which registers with the at least one port of the piston in select conditions.
 18. The torque converter of claim 17, wherein each recess has an open radially inner end and a closed radially outer end such that as the driven and driving components turn relative to one another, each port communicates with each recess once during each complete revolution of the components.
 19. The torque converter of claim 18, wherein when pressure in the second plenum chamber rises above that of the pressure in the first plenum chamber, fluid in the second plenum chamber deforms the bellows whenever the port fluidly communicates with the adjacent recess so that an amount of fluid can flow in the recesses radially inward and into the first plenum chamber.
 20. The torque converter of claim 1, wherein the at least one active means includes at least one expandable bellows that is carried by an outer wall of the housing with the friction liner being carried by a piston that forms a part of the by-pass clutch, the bellows defining at least one internal space which can receive and discharge a quantity of fluid.
 21. The torque converter of claim 20, wherein the outer wall contains at least one port that is in fluid communication with the at least one internal space to permit the fluid to enter and flow from the internal space.
 22. The torque converter of claim 21, wherein the cooling grooves are in the form of a recess formed in the friction liner, a portion of the recess being in registration with the at least one port of the outer wall in select conditions.
 23. The torque converter of claim 22, wherein each recess has an open radially inner end and a closed radially outer end such that as the driven and driving components turn relative to one another, each port communicates with each recess once during each complete revolution of the components.
 24. A hydrokinetic torque converter, comprising: a housing rotatable about a predetermined axis; a pump rotatable by said housing about said axis; a turbine rotatable in said housing about said axis by and relative to said pump; means for rotating said housing; an output element rotatable about said axis and arranged to receive torque from said turbine; a fluid-operated bypass clutch disposed in said housing and arranged to transmit variable torque between said housing and said output element, said clutch including a driving component rotatable with said housing and a driven component rotatable with said output element and movable axially of said housing into and from frictional engagement—with and without slip—with said driving component; means for moving said driven component, including first and second plenum chambers containing bodies of hydraulic fluid at variable pressure with the provision for fluid flow between said chambers through said clutch; and at least one active means for regulating the fluid flow between said chambers by permitting the hydraulic fluid to intermittently flow from one plenum chamber to the other plenum chamber when the components are in selected registration with one another.
 25. The torque converter of claim 24, wherein the at least one active means includes cooling grooves formed in a friction liner associated with one of the components such that when the cooling grooves are in registration with fluid receiving features formed as part of the other component, the fluid flows between the plenum chambers.
 26. The torque converter of claim 24, wherein the selected registration occurs once during each complete revolution of the components relative to one another so as to create an intermittent stream of the fluid from one plenum chamber to the other plenum chamber. 